path: root/usr.sbin/sendmail/doc/usenix/usenix.ps

%!PS-Adobe-3.0
%%Creator: groff version 1.10
%%CreationDate: Tue Dec 29 09:59:22 1998
%%DocumentNeededResources: font Times-Roman
%%+ font Times-Italic
%%+ font Times-Bold
%%DocumentSuppliedResources: procset grops 1.10 0
%%Pages: 9
%%PageOrder: Ascend
%%Orientation: Portrait
%%EndComments
%%BeginProlog
%%BeginResource: procset grops 1.10 0
/setpacking where{
pop
currentpacking
true setpacking
}if
/grops 120 dict dup begin
/SC 32 def
/A/show load def
/B{0 SC 3 -1 roll widthshow}bind def
/C{0 exch ashow}bind def
/D{0 exch 0 SC 5 2 roll awidthshow}bind def
/E{0 rmoveto show}bind def
/F{0 rmoveto 0 SC 3 -1 roll widthshow}bind def
/G{0 rmoveto 0 exch ashow}bind def
/H{0 rmoveto 0 exch 0 SC 5 2 roll awidthshow}bind def
/I{0 exch rmoveto show}bind def
/J{0 exch rmoveto 0 SC 3 -1 roll widthshow}bind def
/K{0 exch rmoveto 0 exch ashow}bind def
/L{0 exch rmoveto 0 exch 0 SC 5 2 roll awidthshow}bind def
/M{rmoveto show}bind def
/N{rmoveto 0 SC 3 -1 roll widthshow}bind def
/O{rmoveto 0 exch ashow}bind def
/P{rmoveto 0 exch 0 SC 5 2 roll awidthshow}bind def
/Q{moveto show}bind def
/R{moveto 0 SC 3 -1 roll widthshow}bind def
/S{moveto 0 exch ashow}bind def
/T{moveto 0 exch 0 SC 5 2 roll awidthshow}bind def
/SF{
findfont exch
[exch dup 0 exch 0 exch neg 0 0]makefont
dup setfont
[exch/setfont cvx]cvx bind def
}bind def
/MF{
findfont
[5 2 roll
0 3 1 roll
neg 0 0]makefont
dup setfont
[exch/setfont cvx]cvx bind def
}bind def
/level0 0 def
/RES 0 def
/PL 0 def
/LS 0 def
/MANUAL{
statusdict begin/manualfeed true store end
}bind def
/PLG{
gsave newpath clippath pathbbox grestore
exch pop add exch pop
}bind def
/BP{
/level0 save def
1 setlinecap
1 setlinejoin
72 RES div dup scale
LS{
90 rotate
}{
0 PL translate
}ifelse
1 -1 scale
}bind def
/EP{
level0 restore
showpage
}bind def
/DA{
newpath arcn stroke
}bind def
/SN{
transform
.25 sub exch .25 sub exch
round .25 add exch round .25 add exch
itransform
}bind def
/DL{
SN
moveto
SN
lineto stroke
}bind def
/DC{
newpath 0 360 arc closepath
}bind def
/TM matrix def
/DE{
TM currentmatrix pop
translate scale newpath 0 0 .5 0 360 arc closepath
TM setmatrix
}bind def
/RC/rcurveto load def
/RL/rlineto load def
/ST/stroke load def
/MT/moveto load def
/CL/closepath load def
/FL{
currentgray exch setgray fill setgray
}bind def
/BL/fill load def
/LW/setlinewidth load def
/RE{
findfont
dup maxlength 1 index/FontName known not{1 add}if dict begin
{
1 index/FID ne{def}{pop pop}ifelse
}forall
/Encoding exch def
dup/FontName exch def
currentdict end definefont pop
}bind def
/DEFS 0 def
/EBEGIN{
moveto
DEFS begin
}bind def
/EEND/end load def
/CNT 0 def
/level1 0 def
/PBEGIN{
/level1 save def
translate
div 3 1 roll div exch scale
neg exch neg exch translate
0 setgray
0 setlinecap
1 setlinewidth
0 setlinejoin
10 setmiterlimit
[]0 setdash
/setstrokeadjust where{
pop
false setstrokeadjust
}if
/setoverprint where{
pop
false setoverprint
}if
newpath
/CNT countdictstack def
userdict begin
/showpage{}def
}bind def
/PEND{
clear
countdictstack CNT sub{end}repeat
level1 restore
}bind def
end def
/setpacking where{
pop
setpacking
}if
%%EndResource
%%IncludeResource: font Times-Roman
%%IncludeResource: font Times-Italic
%%IncludeResource: font Times-Bold
grops begin/DEFS 1 dict def DEFS begin/u{.001 mul}bind def end/RES 72
def/PL 792 def/LS false def/ENC0[/asciicircum/asciitilde/Scaron/Zcaron
/scaron/zcaron/Ydieresis/trademark/quotesingle/.notdef/.notdef/.notdef
/.notdef/.notdef/.notdef/.notdef/.notdef/.notdef/.notdef/.notdef/.notdef
/.notdef/.notdef/.notdef/.notdef/.notdef/.notdef/.notdef/.notdef/.notdef
/.notdef/.notdef/space/exclam/quotedbl/numbersign/dollar/percent
/ampersand/quoteright/parenleft/parenright/asterisk/plus/comma/hyphen
/period/slash/zero/one/two/three/four/five/six/seven/eight/nine/colon
/semicolon/less/equal/greater/question/at/A/B/C/D/E/F/G/H/I/J/K/L/M/N/O
/P/Q/R/S/T/U/V/W/X/Y/Z/bracketleft/backslash/bracketright/circumflex
/underscore/quoteleft/a/b/c/d/e/f/g/h/i/j/k/l/m/n/o/p/q/r/s/t/u/v/w/x/y
/z/braceleft/bar/braceright/tilde/.notdef/quotesinglbase/guillemotleft
/guillemotright/bullet/florin/fraction/perthousand/dagger/daggerdbl
/endash/emdash/ff/fi/fl/ffi/ffl/dotlessi/dotlessj/grave/hungarumlaut
/dotaccent/breve/caron/ring/ogonek/quotedblleft/quotedblright/oe/lslash
/quotedblbase/OE/Lslash/.notdef/exclamdown/cent/sterling/currency/yen
/brokenbar/section/dieresis/copyright/ordfeminine/guilsinglleft
/logicalnot/minus/registered/macron/degree/plusminus/twosuperior
/threesuperior/acute/mu/paragraph/periodcentered/cedilla/onesuperior
/ordmasculine/guilsinglright/onequarter/onehalf/threequarters
/questiondown/Agrave/Aacute/Acircumflex/Atilde/Adieresis/Aring/AE
/Ccedilla/Egrave/Eacute/Ecircumflex/Edieresis/Igrave/Iacute/Icircumflex
/Idieresis/Eth/Ntilde/Ograve/Oacute/Ocircumflex/Otilde/Odieresis
/multiply/Oslash/Ugrave/Uacute/Ucircumflex/Udieresis/Yacute/Thorn
/germandbls/agrave/aacute/acircumflex/atilde/adieresis/aring/ae/ccedilla
/egrave/eacute/ecircumflex/edieresis/igrave/iacute/icircumflex/idieresis
/eth/ntilde/ograve/oacute/ocircumflex/otilde/odieresis/divide/oslash
/ugrave/uacute/ucircumflex/udieresis/yacute/thorn/ydieresis]def
/Times-Bold@0 ENC0/Times-Bold RE/Times-Italic@0 ENC0/Times-Italic RE
/Times-Roman@0 ENC0/Times-Roman RE
%%EndProlog
%%Page: 1 1
%%BeginPageSetup
BP
%%EndPageSetup
/F0 14/Times-Roman@0 SF(Mail Systems and Addressing)204.196 141 Q
(in 4.2bsd)262.331 157.8 Q/F1 10/Times-Roman@0 SF(Eric Allman*)260.92
181.8 Q/F2 10/Times-Italic@0 SF(Britton-Lee)254.86 199.8 Q 2.5(,I)-.1 G
(nc.)-2.5 E(1919 Addison Str)225.13 211.8 Q(eet, Suite 105.)-.37 E(Berk)
232.645 223.8 Q(ele)-.1 E 1.1 -.55(y, C)-.3 H(alifornia 94704.).55 E F1
(eric@Berk)244.175 241.8 Q(ele)-.1 E -.65(y.)-.15 G(ARP).65 E(A)-.92 E
(ucb)264.6 253.8 Q -.25(va)-.15 G(x!eric).25 E(ABSTRA)262.085 286.2 Q
(CT)-.4 E .966
(Routing mail through a heterogeneous internet presents man)112 302.4 R
3.466(yn)-.15 G 1.466 -.25(ew p)-3.466 H 3.466(roblems. Among).25 F .297
(the w)112 314.4 R .297(orst of these is that of address mapping.)-.1 F
(Historically)5.297 E 2.797(,t)-.65 G .298(his has been handled on an)
-2.797 F(ad hoc basis.)112 326.4 Q(Ho)5 E(we)-.25 E -.15(ve)-.25 G .8
-.4(r, t).15 H(his approach has become unmanageable as internets gro).4
E -.65(w.)-.25 G .099(Sendmail acts a uni\214ed \231post of)112 342.6 R
.098(\214ce\232 to which all mail can be submitted.)-.25 F .098
(Address inter)5.098 F(-)-.2 E .754(pretation is controlled by a production system, which can parse both old and ne)
112 354.6 R 3.255(wf)-.25 G(or)-3.255 E(-)-.2 E .242(mat addresses.)112
366.6 R .242(The ne)5.242 F 2.742(wf)-.25 G .242
(ormat is \231domain-based,)-2.742 F 2.742<9a618d>-.7 G -.15(ex)-2.742 G
.241(ible technique that can handle).15 F(man)112 378.6 Q 2.606(yc)-.15
G .106(ommon situations.)-2.606 F .106
(Sendmail is not intended to perform user interf)5.106 F .107
(ace functions.)-.1 F .399(Sendmail will replace deli)112 394.8 R -.15
(ve)-.25 G .399(rmail in the Berk).15 F(ele)-.1 E 2.899(y4)-.15 G .399
(.2 distrib)-2.899 F 2.899(ution. Se)-.2 F -.15(ve)-.25 G .399
(ral major hosts).15 F .421(are no)112 406.8 R 2.921(wo)-.25 G 2.921(rw)
-2.921 G .421(ill soon be running sendmail.)-2.921 F .421
(This change will af)5.421 F .422(fect an)-.25 F 2.922(yu)-.15 G .422
(sers that route)-2.922 F 1.5(mail through a sendmail g)112 418.8 R(ate)
-.05 E -.1(wa)-.25 G 5.3 -.65(y. T).1 H 1.5
(he changes that will be user visible are empha-).65 F(sized.)112 430.8
Q .906
(The mail system to appear in 4.2bsd will contain a number of changes.)
97 475.2 R .906(Most of these changes are)5.906 F .469
(based on the replacement of)72 487.2 R F2(delivermail)2.969 E F1 .469
(with a ne)2.969 F 2.969(wm)-.25 G .469(odule called)-2.969 F F2 2.97
(sendmail. Sendmail)2.97 F F1 .47(implements a gen-)2.97 F 1.834
(eral internetw)72 499.2 R 1.834(ork mail routing f)-.1 F(acility)-.1 E
4.333(,f)-.65 G 1.833(eaturing aliasing and forw)-4.333 F 1.833
(arding, automatic routing to netw)-.1 F(ork)-.1 E -.05(ga)72 511.2 S
(te).05 E -.1(wa)-.25 G .205(ys, and \215e).1 F .205
(xible con\214guration.)-.15 F .205(Of k)5.205 F .505 -.15(ey i)-.1 H
.205(nterest to the mail system user will be the changes in the net-).15
F -.1(wo)72 523.2 S(rk addressing structure.).1 E .624(In a simple netw)
97 539.4 R .624(ork, each node has an address, and resources can be identi\214ed with a host-resource)
-.1 F .374(pair; in particular)72 551.4 R 2.874(,t)-.4 G .374
(he mail system can refer to users using a host-username pair)-2.874 F
5.374(.H)-.55 G .375(ost names and numbers)-5.374 F(ha)72 563.4 Q .3
-.15(ve t)-.2 H 2.5(ob).15 G 2.5(ea)-2.5 G
(dministered by a central authority)-2.5 E 2.5(,b)-.65 G
(ut usernames can be assigned locally to each host.)-2.7 E .397
(In an internet, multiple netw)97 579.6 R .396(orks with dif)-.1 F .396
(ferent characteristics and managements must communicate.)-.25 F .389
(In particular)72 591.6 R 2.889(,t)-.4 G .389
(he syntax and semantics of resource identi\214cation change.)-2.889 F
.39(Certain special cases can be han-)5.389 F 1.033(dled tri)72 603.6 R
1.033(vially by)-.25 F F2 1.033(ad hoc)3.533 F F1 1.032
(techniques, such as pro)3.533 F 1.032(viding netw)-.15 F 1.032
(ork names that appear local to hosts on other)-.1 F(netw)72 615.6 Q
1.621(orks, as with the Ethernet at Xerox P)-.1 F 4.121(ARC. Ho)-.92 F
(we)-.25 E -.15(ve)-.25 G 2.421 -.4(r, t).15 H 1.622
(he general case is e).4 F 1.622(xtremely comple)-.15 F 4.122(x. F)-.15
F(or)-.15 E -.15(ex)72 627.6 S .29(ample, some netw).15 F .29
(orks require that the route the message tak)-.1 F .29(es be e)-.1 F .29
(xplicitly speci\214ed by the sender)-.15 F 2.79(,s)-.4 G(im-)-2.79 E
1.618(plifying the database update problem since only adjacent hosts must be entered into the system tables,)
72 639.6 R .573(while others use logical addressing, where the sender speci\214es the location of the recipient b)
72 651.6 R .573(ut not ho)-.2 F 3.072(wt)-.25 G(o)-3.072 E 1.065
(get there.)72 663.6 R 1.065(Some netw)6.065 F 1.066
(orks use a left-associati)-.1 F 1.366 -.15(ve s)-.25 H 1.066
(yntax and others use a right-associati).15 F 1.366 -.15(ve s)-.25 H
1.066(yntax, causing).15 F .32 LW 76 673.2 72 673.2 DL 80 673.2 76 673.2
DL 84 673.2 80 673.2 DL 88 673.2 84 673.2 DL 92 673.2 88 673.2 DL 96
673.2 92 673.2 DL 100 673.2 96 673.2 DL 104 673.2 100 673.2 DL 108 673.2
104 673.2 DL 112 673.2 108 673.2 DL 116 673.2 112 673.2 DL 120 673.2 116
673.2 DL 124 673.2 120 673.2 DL 128 673.2 124 673.2 DL 132 673.2 128
673.2 DL 136 673.2 132 673.2 DL 140 673.2 136 673.2 DL 144 673.2 140
673.2 DL 148 673.2 144 673.2 DL 152 673.2 148 673.2 DL 156 673.2 152
673.2 DL 160 673.2 156 673.2 DL 164 673.2 160 673.2 DL 168 673.2 164
673.2 DL 172 673.2 168 673.2 DL 176 673.2 172 673.2 DL 180 673.2 176
673.2 DL 184 673.2 180 673.2 DL 188 673.2 184 673.2 DL 192 673.2 188
673.2 DL 196 673.2 192 673.2 DL 200 673.2 196 673.2 DL 204 673.2 200
673.2 DL 208 673.2 204 673.2 DL 212 673.2 208 673.2 DL 216 673.2 212
673.2 DL/F3 8/Times-Roman@0 SF .556(*A considerable part of this w)93.6
685.2 R .556(ork w)-.08 F .556(as done while under the emplo)-.08 F
2.557(yo)-.08 G 2.557(ft)-2.557 G .557(he INGRES Project at the Uni)
-2.557 F -.12(ve)-.2 G .557(rsity of California at).12 F(Berk)72 694.8 Q
(ele)-.08 E -.52(y.)-.12 G/F4 10/Times-Bold@0 SF(Mail Systems and Addr)
72 756 Q(essing in 4.2bsd)-.18 E(1)259.93 E EP
%%Page: 2 2
%%BeginPageSetup
BP
%%EndPageSetup
/F0 10/Times-Bold@0 SF(Mail Systems and Addr)72 60 Q(essing in 4.2bsd)
-.18 E(2)259.93 E/F1 10/Times-Roman@0 SF(ambiguity in mix)72 96 Q
(ed addresses.)-.15 E .679
(Internet standards seek to eliminate these problems.)97 112.2 R
(Initially)5.678 E 3.178(,t)-.65 G .678(hese proposed e)-3.178 F .678
(xpanding the address)-.15 F .331
(pairs to address triples, consisting of {netw)72 124.2 R .331
(ork, host, username} triples.)-.1 F(Netw)5.332 E .332
(ork numbers must be uni)-.1 F -.15(ve)-.25 G -.2(r-).15 G 1.452
(sally agreed upon, and hosts can be assigned locally on each netw)72
136.2 R 3.952(ork. The)-.1 F(user)3.952 E(-le)-.2 E -.15(ve)-.25 G 3.952
(lp).15 G 1.452(resentation w)-3.952 F(as)-.1 E .249(changed to address domains, comprised of a local resource identi\214cation and a hierarchical domain speci\214-)
72 148.2 R 1.54(cation with a common static root.)72 160.2 R 1.539
(The domain technique separates the issue of ph)6.539 F 1.539(ysical v)
-.05 F 1.539(ersus logical)-.15 F 3.001(addressing. F)72 172.2 R .501
(or e)-.15 F .502(xample, an address of the form \231eric@a.cc.berk)-.15
F(ele)-.1 E -.65(y.)-.15 G .502(arpa\232 describes the logical or).65 F
-.05(ga)-.18 G(niza-).05 E .443(tion of the address space \(user \231eric\232 on host \231a\232 in the Computer Center at Berk)
72 184.2 R(ele)-.1 E .443(y\) b)-.15 F .443(ut not the ph)-.2 F(ysical)
-.05 E(netw)72 196.2 Q .934(orks used \(for e)-.1 F .934
(xample, this could go o)-.15 F -.15(ve)-.15 G 3.434(rd).15 G(if)-3.434
E .934(ferent netw)-.25 F .935
(orks depending on whether \231a\232 were on an)-.1 F
(ethernet or a store-and-forw)72 208.2 Q(ard netw)-.1 E(ork\).)-.1 E/F2
10/Times-Italic@0 SF(Sendmail)97 224.4 Q F1 .493
(is intended to help bridge the g)2.993 F .493(ap between the totally)
-.05 F F2 .493(ad hoc)2.993 F F1 -.1(wo)2.993 G .493(rld of netw).1 F
.493(orks that kno)-.1 F(w)-.25 E .854
(nothing of each other and the clean, tightly-coupled w)72 236.4 R .854
(orld of unique netw)-.1 F .855(ork numbers.)-.1 F .855
(It can accept old)5.855 F .633(arbitrary address syntax)72 248.4 R .632
(es, resolving ambiguities using heuristics speci\214ed by the system administrator)
-.15 F 3.132(,a)-.4 G(s)-3.132 E .347(well as domain-based addressing.)
72 260.4 R .347(It helps guide the con)5.347 F -.15(ve)-.4 G .347
(rsion of message formats between disparate net-).15 F -.1(wo)72 272.4 S
3.395(rks. In).1 F(short,)3.395 E F2(sendmail)3.395 E F1 .894
(is designed to assist a graceful transition to consistent internetw)
3.395 F .894(ork addressing)-.1 F(schemes.)72 284.4 Q .689
(Section 1 de\214nes some of the terms frequently left fuzzy when w)97
312.6 R .69(orking in mail systems.)-.1 F .69(Section 2)5.69 F .595
(discusses the design goals for)72 324.6 R F2(sendmail)3.095 E F1 5.595
(.I)C 3.095(ns)-5.595 G .595(ection 3, the ne)-3.095 F 3.095(wa)-.25 G
.594(ddress formats and basic features of)-3.095 F F2(send-)3.094 E
(mail)72 336.6 Q F1 .893(are described.)3.393 F .893
(Section 4 discusses some of the special problems of the UUCP netw)5.893
F 3.394(ork. The)-.1 F(dif)3.394 E(fer)-.25 E(-)-.2 E(ences between)72
348.6 Q F2(sendmail)2.5 E F1(and)2.5 E F2(delivermail)2.5 E F1
(are presented in section 5.)2.5 E F0(DISCLAIMER:)112 376.8 Q F1 3.333
(An)3.333 G .833(umber of e)-3.333 F .832
(xamples in this paper use names of actual people and)-.15 F(or)112
388.8 Q -.05(ga)-.18 G 4.572(nizations. This).05 F 2.072
(is not intended to imply a commitment or e)4.572 F -.15(ve)-.25 G 4.573
(na).15 G 4.573(ni)-4.573 G(ntellectual)-4.573 E 1.094
(agreement on the part of these people or or)112 400.8 R -.05(ga)-.18 G
3.594(nizations. In).05 F(particular)3.594 E 3.594(,B)-.4 G 1.094(ell T)
-3.594 F(elephone)-.7 E .656
(Laboratories \(BTL\), Digital Equipment Corporation \(DEC\), La)112
412.8 R .657(wrence Berk)-.15 F(ele)-.1 E 3.157(yL)-.15 G(abo-)-3.157 E
2.136(ratories \(LBL\), Britton-Lee Incorporated \(BLI\), and the Uni)
112 424.8 R -.15(ve)-.25 G 2.136(rsity of California at).15 F(Berk)112
436.8 Q(ele)-.1 E 3.088(ya)-.15 G .588(re not committed to an)-3.088 F
3.089(yo)-.15 G 3.089(ft)-3.089 G .589(hese proposals at this time.)
-3.089 F .589(Much of this paper)5.589 F
(represents no more than the personal opinions of the author)112 448.8 Q
(.)-.55 E F0 2.5(1. DEFINITIONS)72 477 R F1 .266(There are four basic concepts that must be clearly distinguished when dealing with mail systems:)
112 493.2 R .514(the user \(or the user')87 505.2 R 3.014(sa)-.55 G .515
(gent\), the user')-3.014 F 3.015(si)-.55 G .515
(denti\214cation, the user')-3.015 F 3.015(sa)-.55 G .515
(ddress, and the route.)-3.015 F .515(These are dis-)5.515 F
(tinguished primarily by their position independence.)87 517.2 Q F0 2.5
(1.1. User)87 541.2 R(and Identi\214cation)2.5 E F1 .264(The user is the being \(a person or program\) that is creating or recei)
127 557.4 R .263(ving a message.)-.25 F(An)5.263 E F2 -.1(age)2.763 G
(nt).1 E F1 .659(is an entity operating on behalf of the user \212 such as a secretary who handles my mail.)
102 569.4 R .66(or a pro-)5.66 F(gram that automatically returns a message such as \231I am at the UNICOM conference.)
102 581.4 Q<9a>-.7 E .931(The identi\214cation is the tag that goes along with the particular user)
127 597.6 R 5.931(.T)-.55 G .931(his tag is completely)-5.931 F .216
(independent of location.)102 609.6 R -.15(Fo)5.216 G 2.716(re).15 G
.216(xample, my identi\214cation is the string \231Eric Allman,)-2.866 F
2.717<9a61>-.7 G .217(nd this identi-)-2.717 F 1.228
(\214cation does not change whether I am located at U.C. Berk)102 621.6
R(ele)-.1 E 2.527 -.65(y, a)-.15 H 3.727(tB).65 G 1.227
(ritton-Lee, or at a scienti\214c)-3.727 F(institute in Austria.)102
633.6 Q 2.379(Since the identi\214cation is frequently ambiguous \(e.g., there are tw)
127 649.8 R 4.879<6f99>-.1 G 2.38(Robert Henry\232s at)-4.879 F(Berk)102
661.8 Q(ele)-.1 E .316(y\) it is common to add other disambiguating information that is not strictly part of the iden-)
-.15 F(ti\214cation \(e.g., Robert \231Code Generator\232 Henry v)102
673.8 Q(ersus Robert \231System Administrator\232 Henry\).)-.15 E F0 -1
(Ve)72 756 S(rsion 8.2)1 E(USENIX \255 J)130.475 E(an 83)-.15 E
(Last Mod 11/27/1993)88.355 E EP
%%Page: 3 3
%%BeginPageSetup
BP
%%EndPageSetup
/F0 10/Times-Bold@0 SF(Mail Systems and Addr)72 60 Q(essing in 4.2bsd)
-.18 E(3)259.93 E 2.5(1.2. Addr)87 96 R(ess)-.18 E/F1 10/Times-Roman@0
SF .785(The address speci\214es a location.)127 112.2 R .786(As I mo)
5.786 F 1.086 -.15(ve a)-.15 H .786(round, my address changes.).15 F
-.15(Fo)5.786 G 3.286(re).15 G .786(xample, my)-3.436 F .749
(address might change from \231eric@Berk)102 124.2 R(ele)-.1 E -.65(y.)
-.15 G(ARP).65 E .749
(A\232 to \231eric@bli.UUCP\232 or \231allman@IIASA.Aus-)-.92 F
(tria\232 depending on my current af)102 136.2 Q(\214liation.)-.25 E(Ho)
127 152.4 Q(we)-.25 E -.15(ve)-.25 G 2.819 -.4(r, a).15 H 4.519(na).4 G
2.019(ddress is independent of the location of an)-4.519 F 2.019
(yone else.)-.15 F 2.02(That is, my address)7.02 F .385
(remains the same to e)102 164.4 R -.15(ve)-.25 G .385
(ryone who might be sending me mail.).15 F -.15(Fo)5.385 G 2.885(re).15
G .385(xample, a person at MIT and a)-3.035 F
(person at USC could both send to \231eric@Berk)102 176.4 Q(ele)-.1 E
-.65(y.)-.15 G(ARP).65 E(A\232 and ha)-.92 E .3 -.15(ve i)-.2 H 2.5(ta)
.15 G(rri)-2.5 E .3 -.15(ve t)-.25 H 2.5(ot).15 G(he same mailbox.)-2.5
E .627(Ideally a \231white pages\232 service w)127 192.6 R .627
(ould be pro)-.1 F .627
(vided to map user identi\214cations into addresses)-.15 F .444(\(for e)
102 204.6 R .444(xample, see [Solomon81]\).)-.15 F .444
(Currently this is handled by passing around scraps of paper or by)5.444
F(calling people on the telephone to \214nd out their address.)102 216.6
Q F0 2.5(1.3. Route)87 240.6 R F1 .288(While an address speci\214es)127
256.8 R/F2 10/Times-Italic@0 SF(wher)2.788 E(e)-.37 E F1 .289
(to \214nd a mailbox, a route speci\214es)2.789 F F2(how)2.789 E F1 .289
(to \214nd the mailbox.)2.789 F(Speci\214cally)102 268.8 Q 2.607(,i)-.65
G 2.607(ts)-2.607 G .106(peci\214es a path from sender to recei)-2.607 F
-.15(ve)-.25 G 3.706 -.55(r. A).15 H 2.606(ss).55 G .106
(uch, the route is potentially dif)-2.606 F .106(ferent for)-.25 F -2.15
-.25(ev e)102 280.8 T(ry pair of people in the electronic uni).25 E -.15
(ve)-.25 G(rse.).15 E .258
(Normally the route is hidden from the user by the softw)127 297 R 2.758
(are. Ho)-.1 F(we)-.25 E -.15(ve)-.25 G 1.058 -.4(r, s).15 H .258
(ome netw).4 F .258(orks put the)-.1 F -.2(bu)102 309 S 1.972
(rden of determining the route onto the sender).2 F 6.971(.A)-.55 G
1.971(lthough this simpli\214es the softw)-6.971 F 1.971(are, it also)
-.1 F(greatly impairs the usability for most users.)102 321 Q
(The UUCP netw)5 E(ork is an e)-.1 E(xample of such a netw)-.15 E(ork.)
-.1 E F0 2.5(2. DESIGN)72 345 R(GO)2.5 E(ALS)-.4 E F1(Design goals for)
112 363.2 Q F2(sendmail)2.5 E/F3 7/Times-Roman@0 SF(1)-4 I F1(include:)
2.5 4 M 12.5(\(1\) Compatibility)92 379.4 R 1.363(with the e)3.863 F
1.363(xisting mail programs, including Bell v)-.15 F 1.363
(ersion 6 mail, Bell v)-.15 F 1.364(ersion 7)-.15 F 3.589(mail, Berk)
118.66 391.4 R(ele)-.1 E(y)-.15 E F2(Mail)6.089 E F1 3.589
([Shoens79], BerkNet mail [Schmidt79], and hopefully UUCP mail)6.089 F
([No)118.66 403.4 Q 2.5(witz78]. ARP)-.25 F(ANET mail [Crock)-.92 E
(er82] w)-.1 E(as also required.)-.1 E 12.5(\(2\) Reliability)92 419.6 R
4.002(,i)-.65 G 4.002(nt)-4.002 G 1.502(he sense of guaranteeing that e)
-4.002 F -.15(ve)-.25 G 1.502(ry message is correctly deli).15 F -.15
(ve)-.25 G 1.503(red or at least).15 F .368(brought to the attention of a human for correct disposal; no message should e)
118.66 431.6 R -.15(ve)-.25 G 2.868(rb).15 G 2.868(ec)-2.868 G
(ompletely)-2.868 E 2.54(lost. This)118.66 443.6 R .04(goal w)2.54 F
.041(as considered essential because of the emphasis on mail in our en)
-.1 F 2.541(vironment. It)-.4 F 1.755
(has turned out to be one of the hardest goals to satisfy)118.66 455.6 R
4.254(,e)-.65 G 1.754(specially in the f)-4.254 F 1.754(ace of the man)
-.1 F(y)-.15 E .977(anomalous message formats produced by v)118.66 467.6
R .977(arious ARP)-.25 F .977(ANET sites.)-.92 F -.15(Fo)5.977 G 3.478
(re).15 G .978(xample, certain sites)-3.628 F .069
(generate improperly formated addresses, occasionally causing error)
118.66 479.6 R .069(-message loops.)-.2 F .068(Some hosts)5.069 F .766(use blanks in names, causing problems with mail programs that assume that an address is one)
118.66 491.6 R -.1(wo)118.66 503.6 S 3.924(rd. The).1 F 1.423
(semantics of some \214elds are interpreted slightly dif)3.923 F 1.423
(ferently by dif)-.25 F 1.423(ferent sites.)-.25 F(In)6.423 E(summary)
118.66 515.6 Q 3.022(,t)-.65 G .523(he obscure features of the ARP)
-3.022 F .523(ANET mail protocol really)-.92 F F2(ar)3.023 E(e)-.37 E F1
.523(used and are dif)3.023 F(\214cult)-.25 E(to support, b)118.66 527.6
Q(ut must be supported.)-.2 E 12.5(\(3\) Existing)92 543.8 R(softw)2.939
E .439(are to do actual deli)-.1 F -.15(ve)-.25 G .439
(ry should be used whene).15 F -.15(ve)-.25 G 2.938(rp).15 G 2.938
(ossible. This)-2.938 F .438(goal deri)2.938 F -.15(ve)-.25 G 2.938(sa)
.15 G(s)-2.938 E
(much from political and practical considerations as technical.)118.66
555.8 Q 12.5(\(4\) Easy)92 572 R -.15(ex)2.898 G .398(pansion to f).15 F
.398(airly comple)-.1 F 2.898(xe)-.15 G -.4(nv)-2.898 G .399
(ironments, including multiple connections to a single net-).4 F -.1(wo)
118.66 584 S .63(rk type \(such as with multiple UUCP or Ethernets\).).1
F .63(This goal requires consideration of the)5.63 F(contents of an address as well as its syntax in order to determine which g)
118.66 596 Q(ate)-.05 E -.1(wa)-.25 G 2.5(yt).1 G 2.5(ou)-2.5 G(se.)-2.5
E 12.5(\(5\) Con\214guration)92 612.2 R 1.048
(information should not be compiled into the code.)3.548 F 3.549(As)
6.049 G 1.049(ingle compiled program)-3.549 F .084
(should be able to run as is at an)118.66 624.2 R 2.584(ys)-.15 G .083
(ite \(barring such basic changes as the CPU type or the operat-)-2.584
F .342(ing system\).)118.66 636.2 R 1.942 -.8(We h)5.342 H -2.25 -.2
(av e).8 H .343
(found this seemingly unimportant goal to be critical in real life.)
3.042 F(Besides)5.343 E .734(the simple problems that occur when an)
118.66 648.2 R 3.234(yp)-.15 G .734(rogram gets recompiled in a dif)
-3.234 F .733(ferent en)-.25 F(vironment,)-.4 E(man)118.66 660.2 Q 2.5
(ys)-.15 G(ites lik)-2.5 E 2.5(et)-.1 G 2.5<6f99>-2.5 G
(\214ddle\232 with an)-2.5 E(ything that the)-.15 E 2.5(yw)-.15 G
(ill be recompiling an)-2.5 E(yw)-.15 E(ay)-.1 E(.)-.65 E .32 LW 76
678.8 72 678.8 DL 80 678.8 76 678.8 DL 84 678.8 80 678.8 DL 88 678.8 84
678.8 DL 92 678.8 88 678.8 DL 96 678.8 92 678.8 DL 100 678.8 96 678.8 DL
104 678.8 100 678.8 DL 108 678.8 104 678.8 DL 112 678.8 108 678.8 DL 116
678.8 112 678.8 DL 120 678.8 116 678.8 DL 124 678.8 120 678.8 DL 128
678.8 124 678.8 DL 132 678.8 128 678.8 DL 136 678.8 132 678.8 DL 140
678.8 136 678.8 DL 144 678.8 140 678.8 DL 148 678.8 144 678.8 DL 152
678.8 148 678.8 DL 156 678.8 152 678.8 DL 160 678.8 156 678.8 DL 164
678.8 160 678.8 DL 168 678.8 164 678.8 DL 172 678.8 168 678.8 DL 176
678.8 172 678.8 DL 180 678.8 176 678.8 DL 184 678.8 180 678.8 DL 188
678.8 184 678.8 DL 192 678.8 188 678.8 DL 196 678.8 192 678.8 DL 200
678.8 196 678.8 DL 204 678.8 200 678.8 DL 208 678.8 204 678.8 DL 212
678.8 208 678.8 DL 216 678.8 212 678.8 DL/F4 5/Times-Roman@0 SF(1)93.6
689.2 Q/F5 8/Times-Roman@0 SF(This section mak)3.2 I
(es no distinction between)-.08 E/F6 8/Times-Italic@0 SF(delivermail)2 E
F5(and)2 E F6(sendmail.)2 E F0 -1(Ve)72 756 S(rsion 8.2)1 E
(USENIX \255 J)130.475 E(an 83)-.15 E(Last Mod 11/27/1993)88.355 E EP
%%Page: 4 4
%%BeginPageSetup
BP
%%EndPageSetup
/F0 10/Times-Bold@0 SF(Mail Systems and Addr)72 60 Q(essing in 4.2bsd)
-.18 E(4)259.93 E/F1 10/Times-Roman@0 SF(\(6\))92 96 Q/F2 10
/Times-Italic@0 SF(Sendmail)15 E F1 .184(must be able to let v)2.684 F
.184(arious groups maintain their o)-.25 F .184
(wn mailing lists, and let indi)-.25 F(viduals)-.25 E(specify their o)
118.66 108 Q(wn forw)-.25 E
(arding, without modifying the system alias \214le.)-.1 E 12.5
(\(7\) Each)92 124.2 R .313
(user should be able to specify which mailer to e)2.814 F -.15(xe)-.15 G
.313(cute to process mail being deli).15 F -.15(ve)-.25 G .313(red for)
.15 F 3.098(him. This)118.66 136.2 R .598(feature allo)3.098 F .598
(ws users who are using specialized mailers that use a dif)-.25 F .598
(ferent format to)-.25 F -.2(bu)118.66 148.2 S .25(ild their en).2 F .25
(vironment without changing the system, and f)-.4 F .25
(acilitates specialized functions \(such)-.1 F
(as returning an \231I am on v)118.66 160.2 Q(acation\232 message\).)
-.25 E 12.5(\(8\) Netw)92 176.4 R 1.552(ork traf)-.1 F 1.552(\214c should be minimized by batching addresses to a single host where possible,)
-.25 F(without assistance from the user)118.66 188.4 Q(.)-.55 E .375
(These goals moti)112 204.6 R -.25(va)-.25 G .375
(ted the architecture illustrated in \214gure 1.).25 F .374
(The user interacts with a mail gen-)5.375 F .49
(erating and sending program.)87 216.6 R .491
(When the mail is created, the generator calls)5.49 F F2(sendmail)2.991
E F1 2.991(,w)C .491(hich routes the)-2.991 F .841
(message to the correct mailer\(s\).)87 228.6 R .841
(Since some of the senders may be netw)5.841 F .84(ork serv)-.1 F .84
(ers and some of the)-.15 F(mailers may be netw)87 240.6 Q(ork clients,)
-.1 E F2(sendmail)2.5 E F1(may be used as an internet mail g)2.5 E(ate)
-.05 E -.1(wa)-.25 G -.65(y.).1 G F0 2.5(3. USA)72 264.6 R(GE)-.55 E 2.5
(3.1. Addr)87 288.6 R(ess F)-.18 E(ormats)-.25 E F1(Ar)127 304.8 Q .886
(guments may be \215ags or addresses.)-.18 F .886(Flags set v)5.886 F
.886(arious processing options.)-.25 F -.15(Fo)5.886 G(llo).15 E .886
(wing \215ag)-.25 F(ar)102 316.8 Q .611(guments, address ar)-.18 F .611
(guments may be gi)-.18 F -.15(ve)-.25 G 3.111(n. Addresses).15 F(follo)
3.111 E 3.111(wt)-.25 G .611(he syntax in RFC822 [Crock)-3.111 F(er82])
-.1 E(for ARP)102 328.8 Q(ANET address formats.)-.92 E
(In brief, the format is:)5 E 12.5(\(1\) An)107 345 R
(ything in parentheses is thro)-.15 E(wn a)-.25 E -.1(wa)-.15 G 2.5(y\()
.1 G(as a comment\).)-2.5 E 12.5(\(2\) An)107 361.2 R .051
(ything in angle brack)-.15 F .051(ets \(\231<)-.1 F .051
(>\232\) is preferred o)1.666 F -.15(ve)-.15 G 2.551(ra).15 G -.15(ny)
-2.551 G .051(thing else.).15 F .051(This rule implements the)5.051 F
(ARP)133.66 373.2 Q(ANET standard that addresses of the form)-.92 E .4
LW 77 408 72 408 DL 79 408 74 408 DL 84 408 79 408 DL 89 408 84 408 DL
94 408 89 408 DL 99 408 94 408 DL 104 408 99 408 DL 109 408 104 408 DL
114 408 109 408 DL 119 408 114 408 DL 124 408 119 408 DL 129 408 124 408
DL 134 408 129 408 DL 139 408 134 408 DL 144 408 139 408 DL 149 408 144
408 DL 154 408 149 408 DL 159 408 154 408 DL 164 408 159 408 DL 169 408
164 408 DL 174 408 169 408 DL 179 408 174 408 DL 184 408 179 408 DL 189
408 184 408 DL 194 408 189 408 DL 199 408 194 408 DL 204 408 199 408 DL
209 408 204 408 DL 214 408 209 408 DL 219 408 214 408 DL 224 408 219 408
DL 229 408 224 408 DL 234 408 229 408 DL 239 408 234 408 DL 244 408 239
408 DL 249 408 244 408 DL 254 408 249 408 DL 259 408 254 408 DL 264 408
259 408 DL 269 408 264 408 DL 274 408 269 408 DL 279 408 274 408 DL 284
408 279 408 DL 289 408 284 408 DL 294 408 289 408 DL 299 408 294 408 DL
304 408 299 408 DL 309 408 304 408 DL 314 408 309 408 DL 319 408 314 408
DL 324 408 319 408 DL 329 408 324 408 DL 334 408 329 408 DL 339 408 334
408 DL 344 408 339 408 DL 349 408 344 408 DL 354 408 349 408 DL 359 408
354 408 DL 364 408 359 408 DL 369 408 364 408 DL 374 408 369 408 DL 379
408 374 408 DL 384 408 379 408 DL 389 408 384 408 DL 394 408 389 408 DL
399 408 394 408 DL 404 408 399 408 DL 409 408 404 408 DL 414 408 409 408
DL 419 408 414 408 DL 424 408 419 408 DL 429 408 424 408 DL 434 408 429
408 DL 439 408 434 408 DL 444 408 439 408 DL 449 408 444 408 DL 454 408
449 408 DL 459 408 454 408 DL 464 408 459 408 DL 469 408 464 408 DL 474
408 469 408 DL 479 408 474 408 DL 484 408 479 408 DL 489 408 484 408 DL
494 408 489 408 DL 499 408 494 408 DL 504 408 499 408 DL
(Figure 1 \212 Sendmail System Structure.)208 660 Q 77 672 72 672 DL 79
672 74 672 DL 84 672 79 672 DL 89 672 84 672 DL 94 672 89 672 DL 99 672
94 672 DL 104 672 99 672 DL 109 672 104 672 DL 114 672 109 672 DL 119
672 114 672 DL 124 672 119 672 DL 129 672 124 672 DL 134 672 129 672 DL
139 672 134 672 DL 144 672 139 672 DL 149 672 144 672 DL 154 672 149 672
DL 159 672 154 672 DL 164 672 159 672 DL 169 672 164 672 DL 174 672 169
672 DL 179 672 174 672 DL 184 672 179 672 DL 189 672 184 672 DL 194 672
189 672 DL 199 672 194 672 DL 204 672 199 672 DL 209 672 204 672 DL 214
672 209 672 DL 219 672 214 672 DL 224 672 219 672 DL 229 672 224 672 DL
234 672 229 672 DL 239 672 234 672 DL 244 672 239 672 DL 249 672 244 672
DL 254 672 249 672 DL 259 672 254 672 DL 264 672 259 672 DL 269 672 264
672 DL 274 672 269 672 DL 279 672 274 672 DL 284 672 279 672 DL 289 672
284 672 DL 294 672 289 672 DL 299 672 294 672 DL 304 672 299 672 DL 309
672 304 672 DL 314 672 309 672 DL 319 672 314 672 DL 324 672 319 672 DL
329 672 324 672 DL 334 672 329 672 DL 339 672 334 672 DL 344 672 339 672
DL 349 672 344 672 DL 354 672 349 672 DL 359 672 354 672 DL 364 672 359
672 DL 369 672 364 672 DL 374 672 369 672 DL 379 672 374 672 DL 384 672
379 672 DL 389 672 384 672 DL 394 672 389 672 DL 399 672 394 672 DL 404
672 399 672 DL 409 672 404 672 DL 414 672 409 672 DL 419 672 414 672 DL
424 672 419 672 DL 429 672 424 672 DL 434 672 429 672 DL 439 672 434 672
DL 444 672 439 672 DL 449 672 444 672 DL 454 672 449 672 DL 459 672 454
672 DL 464 672 459 672 DL 469 672 464 672 DL 474 672 469 672 DL 479 672
474 672 DL 484 672 479 672 DL 489 672 484 672 DL 494 672 489 672 DL 499
672 494 672 DL 504 672 499 672 DL F0 -1(Ve)72 756 S(rsion 8.2)1 E
(USENIX \255 J)130.475 E(an 83)-.15 E(Last Mod 11/27/1993)88.355 E EP
%%Page: 5 5
%%BeginPageSetup
BP
%%EndPageSetup
/F0 10/Times-Bold@0 SF(Mail Systems and Addr)72 60 Q(essing in 4.2bsd)
-.18 E(5)259.93 E/F1 10/Times-Roman@0 SF(user name <machine-address>)
173.66 96 Q(will send to the electronic \231machine-address\232 rather than the human \231user name.)
133.66 112.2 Q<9a>-.7 E 12.5(\(3\) Double)107 128.4 R 2.246(quotes \()
4.746 F -2.754 2.5("\) q)2.5 H 2.246
(uote phrases; backslashes quote characters.)-2.5 F 2.246
(Backslashes are more)7.246 F(po)133.66 140.4 Q .654(werful in that the)
-.25 F 3.154(yw)-.15 G .655(ill cause otherwise equi)-3.154 F -.25(va)
-.25 G .655(lent phrases to compare dif).25 F .655(ferently \212 for)
-.25 F -.15(ex)133.66 152.4 S(ample,).15 E/F2 10/Times-Italic@0 SF(user)
3.873 E F1(and)3.873 E F2("user")3.872 E F1 1.372(are equi)3.872 F -.25
(va)-.25 G 1.372(lent, b).25 F(ut)-.2 E F2(\\user)3.872 E F1 1.372
(is dif)3.872 F 1.372(ferent from either of them.)-.25 F(This)6.372 E
(might be used to a)133.66 164.4 Q -.2(vo)-.2 G
(id normal aliasing or duplicate suppression algorithms.).2 E -.15(Pa)
127 180.6 S 1.12(rentheses, angle brack).15 F 1.12
(ets, and double quotes must be properly balanced and nested.)-.1 F(The)
6.12 E(re)102 194.6 Q(writing rules control remaining parsing)-.25 E/F3
7/Times-Roman@0 SF(2)-4 I F1(.)4 I .644(Although old style addresses are still accepted in most cases, the preferred address format is)
127 210.8 R .299(based on ARP)102 222.8 R(ANET)-.92 E .299
(-style domain-based addresses [Su82a].)-.92 F .299
(These addresses are based on a hierar)5.299 F(-)-.2 E .13
(chical, logical decomposition of the address space.)102 234.8 R .13
(The addresses are hierarchical in a sense similar)5.13 F 1.133(to the U.S. postal addresses: the messages may \214rst be routed to the correct state, with no initial)
102 246.8 R .72(consideration of the city or other addressing details.)
102 258.8 R .72(The addresses are logical in that each step in)5.72 F
(the hierarch)102 270.8 Q 2.5(yc)-.05 G
(orresponds to a set of \231naming authorities\232 rather than a ph)-2.5
E(ysical netw)-.05 E(ork.)-.1 E -.15(Fo)127 287 S 2.5(re).15 G
(xample, the address:)-2.65 E(eric@HostA.BigSite.ARP)142 303.2 Q(A)-.92
E -.1(wo)102 319.4 S .851(uld \214rst look up the domain BigSite in the namespace administrated by ARP)
.1 F 3.351(A. A)-.92 F .851(query could)3.351 F 1.476
(then be sent to BigSite for interpretation of HostA.)102 331.4 R(Ev)
6.475 E 1.475(entually the mail w)-.15 F 1.475(ould arri)-.1 F 1.775
-.15(ve a)-.25 H 3.975(tH).15 G(ostA,)-3.975 E(which w)102 343.4 Q
(ould then do \214nal deli)-.1 E -.15(ve)-.25 G(ry to user \231eric.).15
E<9a>-.7 E F0 2.5(3.2. Mail)87 367.4 R(to Files and Pr)2.5 E(ograms)-.18
E F1 .609(Files and programs are le)127 383.6 R .609
(gitimate message recipients.)-.15 F .609(Files pro)5.609 F .609
(vide archi)-.15 F -.25(va)-.25 G 3.109(ls).25 G .61(torage of mes-)
-3.109 F .124(sages, useful for project administration and history)102
395.6 R 5.124(.P)-.65 G .124(rograms are useful as recipients in a v)
-5.124 F .124(ariety of)-.25 F .69(situations, for e)102 407.6 R .691(xample, to maintain a public repository of systems messages \(such as the Berk)
-.15 F(ele)-.1 E(y)-.15 E F2(msgs)102 419.6 Q F1(program\).)2.5 E(An)127
435.8 Q 3.188(ya)-.15 G .688(ddress passing through the initial parsing algorithm as a local address \(i.e, not appear)
-3.188 F(-)-.2 E .276(ing to be a v)102 447.8 R .276
(alid address for another mailer\) is scanned for tw)-.25 F 2.776(os)-.1
G .277(pecial cases.)-2.776 F .277(If pre\214x)5.277 F .277(ed by a v)
-.15 F(erti-)-.15 E .18(cal bar \(\231)102 459.8 R .833<7c9a>.833 G 2.68
(\)t)-.833 G .179
(he rest of the address is processed as a shell command.)-2.68 F .179
(If the user name be)5.179 F .179(gins with a)-.15 F(slash mark \(\231/)
102 471.8 Q
(\232\) the name is used as a \214le name, instead of a login name.).833
E F0 2.5(3.3. Aliasing,)87 495.8 R -.25(Fo)2.5 G(rwarding, Inclusion).25
E F2(Sendmail)127 512 Q F1 1.074(reroutes mail three w)3.574 F 3.574
(ays. Aliasing)-.1 F 1.075(applies system wide.)3.575 F -.15(Fo)6.075 G
(rw).15 E 1.075(arding allo)-.1 F 1.075(ws each)-.25 F .233
(user to reroute incoming mail destined for that account.)102 524 R .233
(Inclusion directs)5.233 F F2(sendmail)2.733 E F1 .233
(to read a \214le for)2.733 F 2.5(al)102 536 S
(ist of addresses, and is normally used in conjunction with aliasing.)
-2.5 E F0 2.5(3.3.1. Aliasing)102 560 R F1 .065(Aliasing maps local addresses to address lists using a system-wide \214le.)
142 576.2 R .065(This \214le is hashed)5.065 F 1.546(to speed access.)
117 588.2 R 1.545(Only addresses that parse as local are allo)6.546 F
1.545(wed as aliases; this guarantees a)-.25 F(unique k)117 600.2 Q .3
-.15(ey \()-.1 H(since there are no nicknames for the local host\).).15
E F0 2.5(3.3.2. F)102 624.2 R(orwarding)-.25 E F1 .641
(After aliasing, if an recipient address speci\214es a local user)142
640.4 R F2(sendmail)3.141 E F1 .641(searches for a \231.for)3.141 F(-)
-.2 E -.1(wa)117 652.4 S .413(rd\232 \214le in the recipient').1 F 2.913
(sh)-.55 G .413(ome directory)-2.913 F 5.413(.I)-.65 G 2.913(fi)-5.413 G
2.913(te)-2.913 G .413(xists, the message is)-3.063 F F2(not)2.913 E F1
.412(sent to that user)2.913 F 2.912(,b)-.4 G(ut)-3.112 E .745
(rather to the list of addresses in that \214le.)117 664.4 R .746
(Often this list will contain only one address, and the)5.746 F
(feature will be used for netw)117 676.4 Q(ork mail forw)-.1 E(arding.)
-.1 E .32 LW 76 686 72 686 DL 80 686 76 686 DL 84 686 80 686 DL 88 686
84 686 DL 92 686 88 686 DL 96 686 92 686 DL 100 686 96 686 DL 104 686
100 686 DL 108 686 104 686 DL 112 686 108 686 DL 116 686 112 686 DL 120
686 116 686 DL 124 686 120 686 DL 128 686 124 686 DL 132 686 128 686 DL
136 686 132 686 DL 140 686 136 686 DL 144 686 140 686 DL 148 686 144 686
DL 152 686 148 686 DL 156 686 152 686 DL 160 686 156 686 DL 164 686 160
686 DL 168 686 164 686 DL 172 686 168 686 DL 176 686 172 686 DL 180 686
176 686 DL 184 686 180 686 DL 188 686 184 686 DL 192 686 188 686 DL 196
686 192 686 DL 200 686 196 686 DL 204 686 200 686 DL 208 686 204 686 DL
212 686 208 686 DL 216 686 212 686 DL/F4 5/Times-Roman@0 SF(2)93.6 696.4
Q/F5 8/Times-Roman@0 SF
(Disclaimer: Some special processing is done after re)3.2 I
(writing local names; see belo)-.2 E -.52(w.)-.2 G F0 -1(Ve)72 756 S
(rsion 8.2)1 E(USENIX \255 J)130.475 E(an 83)-.15 E(Last Mod 11/27/1993)
88.355 E EP
%%Page: 6 6
%%BeginPageSetup
BP
%%EndPageSetup
/F0 10/Times-Bold@0 SF(Mail Systems and Addr)72 60 Q(essing in 4.2bsd)
-.18 E(6)259.93 E/F1 10/Times-Roman@0 SF -.15(Fo)142 96 S(rw).15 E 1.152
(arding also permits a user to specify a pri)-.1 F -.25(va)-.25 G 1.151
(te incoming mailer).25 F 6.151(.F)-.55 G 1.151(or e)-6.301 F 1.151
(xample, for)-.15 F(-)-.2 E -.1(wa)117 108 S(rding to:).1 E -2.5 .833
("| /)157 124.2 T(usr/local/ne)-.833 E(wmail myname")-.25 E
(will use a dif)117 140.4 Q(ferent incoming mailer)-.25 E(.)-.55 E F0
2.5(3.3.3. Inclusion)102 164.4 R F1
(Inclusion is speci\214ed in RFC 733 [Crock)142 180.6 Q(er77] syntax:)
-.1 E(:Include: pathname)157 196.8 Q .391
(An address of this form reads the \214le speci\214ed by)117 213 R/F2 10
/Times-Italic@0 SF(pathname)2.891 E F1 .391
(and sends to all users listed in that)2.891 F(\214le.)117 225 Q .645
(The intent is)142 241.2 R F2(not)3.145 E F1 .644
(to support direct use of this feature, b)3.145 F .644
(ut rather to use this as a subset of)-.2 F 2.5(aliasing. F)117 253.2 R
(or e)-.15 E(xample, an alias of the form:)-.15 E
(project: :include:/usr/project/userlist)157 269.4 Q 1.93(is a method of letting a project maintain a mailing list without interaction with the system)
117 285.6 R(administration, e)117 297.6 Q -.15(ve)-.25 G 2.5(ni).15 G
2.5(ft)-2.5 G(he alias \214le is protected.)-2.5 E 2.025
(It is not necessary to reb)142 313.8 R 2.025(uild the inde)-.2 F 4.524
(xo)-.15 G 4.524(nt)-4.524 G 2.024
(he alias database when a :include: list is)-4.524 F(changed.)117 325.8
Q F0 2.5(3.4. Message)87 349.8 R(Collection)2.5 E F1 .857
(Once all recipient addresses are parsed and v)127 366 R .857
(eri\214ed, the message is collected.)-.15 F .857(The message)5.857 F
.574(comes in tw)102 378 R 3.074(op)-.1 G .574
(arts: a message header and a message body)-3.074 F 3.074(,s)-.65 G .574
(eparated by a blank line.)-3.074 F .573(The body is)5.574 F
(an uninterpreted sequence of te)102 390 Q(xt lines.)-.15 E
(The header is formated as a series of lines of the form)127 406.2 Q
(\214eld-name: \214eld-v)178 422.4 Q(alue)-.25 E(Field-v)102 438.6 Q
1.366(alue can be split across lines by starting the follo)-.25 F 1.366
(wing lines with a space or a tab)-.25 F 6.366(.S)-.4 G(ome)-6.366 E
.211(header \214elds ha)102 450.6 R .511 -.15(ve s)-.2 H .211
(pecial internal meaning, and ha).15 F .511 -.15(ve a)-.2 H .211
(ppropriate special processing.).15 F .21(Other headers)5.21 F
(are simply passed through.)102 462.6 Q
(Some header \214elds may be added automatically)5 E 2.5(,s)-.65 G
(uch as time stamps.)-2.5 E F0 2.5(4. THE)72 486.6 R(UUCP PR)2.5 E
(OBLEM)-.3 E F1 .43(Of particular interest is the UUCP netw)112 502.8 R
2.93(ork. The)-.1 F -.15(ex)2.93 G .43
(plicit routing used in the UUCP en).15 F(vironment)-.4 E .909
(causes a number of serious problems.)87 514.8 R .909(First, gi)5.909 F
.908(ving out an address is impossible without kno)-.25 F .908(wing the)
-.25 F .453(address of your potential correspondent.)87 526.8 R .454
(This is typically handled by specifying the address relati)5.453 F .754
-.15(ve t)-.25 H(o).15 E 1.208(some \231well-kno)87 538.8 R 1.208
(wn\232 host \(e.g., ucb)-.25 F -.25(va)-.15 G 3.708(xo).25 G 3.708(rd)
-3.708 G(ecv)-3.708 E 3.708(ax\). Second,)-.25 F 1.207(it is often dif)
3.708 F 1.207(\214cult to compute the set of)-.25 F .157
(addresses to reply to without some kno)87 550.8 R .157
(wledge of the topology of the netw)-.25 F 2.657(ork. Although)-.1 F
.157(it may be easy)2.657 F .352(for a human being to do this under man)
87 562.8 R 2.851(yc)-.15 G .351(ircumstances, a program does not ha)
-2.851 F .651 -.15(ve e)-.2 H .351(qually sophisticated).15 F 1.153
(heuristics b)87 574.8 R 1.153(uilt in.)-.2 F 1.154(Third, certain addresses will become painfully and unnecessarily long, as when a)
6.153 F .406(message is routed through man)87 586.8 R 2.906(yh)-.15 G
.406(osts in the USENET)-2.906 F 5.406(.A)-.74 G .406(nd \214nally)
-5.406 F 2.905(,c)-.65 G .405(ertain \231mix)-2.905 F .405
(ed domain\232 addresses)-.15 F
(are impossible to parse unambiguously \212 e.g.,)87 598.8 Q(decv)127
615 Q(ax!ucb)-.25 E -.25(va)-.15 G(x!lbl-h!user@LBL-CSAM).25 E .378
(might ha)87 631.2 R .678 -.15(ve m)-.2 H(an).15 E 2.878(yp)-.15 G .379
(ossible resolutions, depending on whether the message w)-2.878 F .379
(as \214rst routed to decv)-.1 F .379(ax or)-.25 F(to LBL-CSAM.)87 643.2
Q 2.32 -.8(To s)112 659.4 T(olv).8 E 3.22(et)-.15 G .72
(his problem, the UUCP syntax w)-3.22 F .719(ould ha)-.1 F 1.019 -.15
(ve t)-.2 H 3.219(ob).15 G 3.219(ec)-3.219 G .719
(hanged to use addresses rather than)-3.219 F 3.718(routes. F)87 671.4 R
1.218(or e)-.15 F 1.218(xample, the address \231decv)-.15 F(ax!ucb)-.25
E -.25(va)-.15 G 1.218(x!eric\232 might be e).25 F 1.218
(xpressed as \231eric@ucb)-.15 F -.25(va)-.15 G(x.UUCP\232).25 E .079
(\(with the hop through decv)87 683.4 R .079(ax implied\).)-.25 F .079
(This address w)5.079 F .078
(ould itself be a domain-based address; for e)-.1 F(xam-)-.15 E
(ple, an address might be of the form:)87 695.4 Q(mark@d.cbosg.btl.UUCP)
127 711.6 Q F0 -1(Ve)72 756 S(rsion 8.2)1 E(USENIX \255 J)130.475 E
(an 83)-.15 E(Last Mod 11/27/1993)88.355 E EP
%%Page: 7 7
%%BeginPageSetup
BP
%%EndPageSetup
/F0 10/Times-Bold@0 SF(Mail Systems and Addr)72 60 Q(essing in 4.2bsd)
-.18 E(7)259.93 E/F1 10/Times-Roman@0 SF .311(Hosts outside of Bell T)87
96 R .311(elephone Laboratories w)-.7 F .311(ould then only need to kno)
-.1 F 2.811(wh)-.25 G .811 -.25(ow t)-2.811 H 2.811(og).25 G .312
(et to a designated)-2.811 F(BTL relay)87 108 Q 2.5(,a)-.65 G
(nd the BTL topology w)-2.5 E(ould only be maintained inside Bell.)-.1 E
.543(There are three major problems associated with turning UUCP addresses into something reason-)
112 124.2 R .465(able: de\214ning the namespace, creating and propag)87
136.2 R .465(ating the necessary softw)-.05 F .466(are, and b)-.1 F .466
(uilding and main-)-.2 F(taining the database.)87 148.2 Q F0 2.5
(4.1. De\214ning)87 172.2 R(the Namespace)2.5 E F1 1.015(Putting all UUCP hosts into a \215at namespace \(e.g., \231...@host.UUCP\232\) is not practical for a)
127 188.4 R .222(number of reasons.)102 200.4 R .222(First, with o)5.222
F -.15(ve)-.15 G 2.722(r1).15 G .222(600 sites already)-2.722 F 2.722
(,a)-.65 G .222(nd \(with the increasing a)-2.722 F -.25(va)-.2 G .222
(ilability of ine).25 F(x-)-.15 E(pensi)102 212.4 Q 1.973 -.15(ve m)-.25
H 1.673(icrocomputers and autodialers\) se).15 F -.15(ve)-.25 G 1.672
(ral thousand more coming within a fe).15 F 4.172(wy)-.25 G 1.672
(ears, the)-4.172 F .078(database update problem is simply intractable if the namespace is \215at.)
102 224.4 R .078(Second, there are almost cer)5.078 F(-)-.2 E 2.446
(tainly name con\215icts today)102 236.4 R 7.446(.T)-.65 G 2.446
(hird, as the number of sites gro)-7.446 F 4.946(wt)-.25 G 2.446
(he names become e)-4.946 F -.15(ve)-.25 G 4.946(rl).15 G(ess)-4.946 E
(mnemonic.)102 248.4 Q .534(It seems ine)127 264.6 R .535(vitable that there be some sort of naming authority for the set of top le)
-.25 F -.15(ve)-.25 G 3.035(ln).15 G(ames)-3.035 E .157
(in the UUCP domain, as unpleasant a possibility as that may seem.)102
276.6 R .157(It will simply not be possible to)5.157 F(ha)102 288.6 Q
.536 -.15(ve o)-.2 H .236(ne host resolving all names.).15 F .236
(It may ho)5.236 F(we)-.25 E -.15(ve)-.25 G 2.736(rb).15 G 2.736(ep)
-2.736 G .236(ossible to handle this in a f)-2.736 F .237
(ashion similar to)-.1 F 1.582(that of assigning names of ne)102 300.6 R
1.582(wsgroups in USENET)-.25 F 6.582(.H)-.74 G -.25(ow)-6.582 G -2.15
-.25(ev e).25 H 2.382 -.4(r, i).25 H 4.082(tw).4 G 1.582
(ill be essential to encourage)-4.082 F -2.15 -.25(ev e)102 312.6 T .52
(ryone to become subdomains of an e).25 F .52(xisting domain whene)-.15
F -.15(ve)-.25 G 3.02(rp).15 G .52(ossible \212 e)-3.02 F -.15(ve)-.25 G
3.02(nt).15 G .52(hough this will)-3.02 F .077(certainly bruise some e)
102 324.6 R 2.577(gos. F)-.15 F .077(or e)-.15 F .077(xample, if a ne)
-.15 F 2.577(wh)-.25 G .076
(ost named \231blid\232 were to be added to the UUCP)-2.577 F(netw)102
336.6 Q .65(ork, it w)-.1 F .651(ould probably actually be addressed as \231d.bli.UUCP\232 \(i.e., as host \231d\232 in the pseudo-)
-.1 F(domain \231bli\232 rather than as host \231blid\232 in the UUCP domain\).)
102 348.6 Q F0 2.5(4.2. Cr)87 372.6 R(eating and Pr)-.18 E
(opagating the Softwar)-.18 E(e)-.18 E F1 .078(The softw)127 388.8 R
.078(are required to implement a consistent namespace is relati)-.1 F
-.15(ve)-.25 G .077(ly tri).15 F 2.577(vial. T)-.25 F .277 -.1(wo m)-.8
H(odules).1 E(are needed, one to handle incoming mail and one to handle outgoing mail.)
102 400.8 Q 1.136
(The incoming module must be prepared to handle either old or ne)127 417
R 3.636(ws)-.25 G 1.136(tyle addresses.)-3.636 F(Ne)6.136 E(w-)-.25 E
.025(style addresses can be passed through unchanged.)102 429 R .024
(Old style addresses must be turned into ne)5.025 F 2.524(ws)-.25 G
(tyle)-2.524 E(addresses where possible.)102 441 Q 2.247
(The outgoing module is slightly trickier)127 457.2 R 7.247(.I)-.55 G
4.747(tm)-7.247 G 2.247(ust do a database lookup on the recipient)-4.747
F .823(addresses \(passed on the command line\) to determine what hosts to send the message to.)
102 469.2 R .823(If those)5.823 F .023(hosts do not accept ne)102 481.2
R .024(w-style addresses, it must transform all addresses in the header of the message)
-.25 F(into old style using the database lookup.)102 493.2 Q 1.197
(Both of these modules are straightforw)127 509.4 R 1.197(ard e)-.1 F
1.197(xcept for the issue of modifying the header)-.15 F 6.197(.I)-.55 G
(t)-6.197 E .944
(seems prudent to choose one format for the message headers.)102 521.4 R
-.15(Fo)5.944 G 3.444(ran).15 G .944(umber of reasons, Berk)-3.444 F
(ele)-.1 E(y)-.15 E .824(has elected to use the ARP)102 533.4 R .824
(ANET protocols for message formats.)-.92 F(Ho)5.823 E(we)-.25 E -.15
(ve)-.25 G 1.623 -.4(r, t).15 H .823(his protocol is some-).4 F
(what dif)102 545.4 Q(\214cult to parse.)-.25 E(Propag)127 561.6 Q 1.903
(ation is some)-.05 F 1.903(what more dif)-.25 F 4.403(\214cult. There)
-.25 F 1.903(are a lar)4.403 F 1.903(ge number of hosts connected to)
-.18 F .812(UUCP that will w)102 573.6 R .811
(ant to run completely standard systems \(for v)-.1 F .811
(ery good reasons\).)-.15 F .811(The strate)5.811 F .811(gy is)-.15 F
(not to con)102 585.6 Q -.15(ve)-.4 G(rt the entire netw).15 E
(ork \212 only enough of it it alle)-.1 E(viate the problem.)-.25 E F0
2.5(4.3. Building)87 609.6 R(and Maintaining the Database)2.5 E F1 .127
(This is by f)127 625.8 R .127(ar the most dif)-.1 F .128
(\214cult problem.)-.25 F 2.628(Ap)5.128 G .128
(rototype for this database already e)-2.628 F .128(xists, b)-.15 F .128
(ut it is)-.2 F(maintained by hand and does not pretend to be complete.)
102 637.8 Q .701(This problem will be reduced considerably if people choose to group their hosts into subdo-)
127 654 R 3.219(mains. This)102 666 R -.1(wo)3.219 G .719
(uld require a global update only when a ne).1 F 3.22(wt)-.25 G .72
(op le)-3.22 F -.15(ve)-.25 G 3.22(ld).15 G .72(omain joined the netw)
-3.22 F(ork.)-.1 E 2.805(Am)102 678 S .305
(essage to a host in a subdomain could simply be routed to a kno)-2.805
F .304(wn domain g)-.25 F(ate)-.05 E -.1(wa)-.25 G 2.804(yf).1 G .304
(or further)-2.804 F 3.073(processing. F)102 690 R .573(or e)-.15 F .573
(xample, the address \231eric@a.bli.UUCP\232 might be routed to the \231bli\232 g)
-.15 F(ate)-.05 E -.1(wa)-.25 G 3.074(yf).1 G(or)-3.074 E(redistrib)102
702 Q 1.376(ution; ne)-.2 F 3.876(wh)-.25 G 1.375
(osts could be added within BLI without notifying the rest of the w)
-3.876 F 3.875(orld. Of)-.1 F(course, other hosts)102 714 Q/F2 10
/Times-Italic@0 SF(could)2.5 E F1(be noti\214ed as an ef)2.5 E
(\214cienc)-.25 E 2.5(ym)-.15 G(easure.)-2.5 E F0 -1(Ve)72 756 S
(rsion 8.2)1 E(USENIX \255 J)130.475 E(an 83)-.15 E(Last Mod 11/27/1993)
88.355 E EP
%%Page: 8 8
%%BeginPageSetup
BP
%%EndPageSetup
/F0 10/Times-Bold@0 SF(Mail Systems and Addr)72 60 Q(essing in 4.2bsd)
-.18 E(8)259.93 E/F1 10/Times-Roman@0 SF .966
(There may be more than one domain g)127 96 R(ate)-.05 E -.1(wa)-.25 G
4.767 -.65(y. A).1 H .967(domain such as BTL, for instance, might)4.117
F(ha)102 108 Q .653 -.15(ve a d)-.2 H .353(ozen g).15 F(ate)-.05 E -.1
(wa)-.25 G .353(ys to the outside w).1 F .352
(orld; a non-BTL site could choose the closest g)-.1 F(ate)-.05 E -.1
(wa)-.25 G 4.152 -.65(y. T).1 H(he).65 E .308(only restriction w)102 120
R .308(ould be that all g)-.1 F(ate)-.05 E -.1(wa)-.25 G .308
(ys maintain a consistent vie).1 F 2.808(wo)-.25 G 2.808(ft)-2.808 G
.308(he domain the)-2.808 F 2.808(yr)-.15 G(epresent.)-2.808 E F0 2.5
(4.4. Logical)87 144 R(Structur)2.5 E(e)-.18 E F1(Logically)127 160.2 Q
3.803(,d)-.65 G 1.303(omains are or)-3.803 F -.05(ga)-.18 G 1.303
(nized into a tree.).05 F 1.303
(There need not be a host actually associated)6.303 F .462(with each le)
102 172.2 R -.15(ve)-.25 G 2.962(li).15 G 2.962(nt)-2.962 G .462
(he tree \212 for e)-2.962 F .462
(xample, there will be no host associated with the name \231UUCP)-.15 F
-.7<2e9a>-1.11 G(Similarly)102 184.2 Q 3.115(,a)-.65 G 3.115(no)-3.115 G
-2.19 -.18(rg a)-3.115 H .614
(nization might group names together for administrati).18 F .914 -.15
(ve r)-.25 H .614(easons; for e).15 F .614(xample, the)-.15 F(name)102
196.2 Q(CAD.research.BigCorp.UUCP)142 212.4 Q(might not actually ha)102
228.6 Q .3 -.15(ve a h)-.2 H(ost representing \231research.).15 E<9a>-.7
E(Ho)127 244.8 Q(we)-.25 E -.15(ve)-.25 G 1.531 -.4(r, i).15 H 3.231(tm)
.4 G .731(ay frequently be con)-3.231 F -.15(ve)-.4 G .731(nient to ha)
.15 F 1.031 -.15(ve a h)-.2 H .732
(ost or hosts that \231represent\232 a domain.).15 F -.15(Fo)102 256.8 S
3.466(re).15 G .966(xample, if a single host e)-3.616 F .966
(xists that represents Berk)-.15 F(ele)-.1 E 2.266 -.65(y, t)-.15 H .966
(hen mail from outside Berk).65 F(ele)-.1 E 3.466(yc)-.15 G(an)-3.466 E
(forw)102 268.8 Q .796
(ard mail to that host for further resolution without kno)-.1 F .796
(wing Berk)-.25 F(ele)-.1 E(y')-.15 E 3.296(s\()-.55 G .797(rather v)
-3.296 F .797(olatile\) topol-)-.2 F(ogy)102 280.8 Q 5(.T)-.65 G
(his is not unlik)-5 E 2.5(et)-.1 G(he operation of the telephone netw)
-2.5 E(ork.)-.1 E .053(This may also be useful inside certain lar)127
297 R .053(ge domains.)-.18 F -.15(Fo)5.053 G 2.553(re).15 G .053
(xample, at Berk)-2.703 F(ele)-.1 E 2.553(yi)-.15 G 2.553(tm)-2.553 G
.053(ay be pre-)-2.553 F .722(sumed that most hosts kno)102 309 R 3.222
(wa)-.25 G .722(bout other hosts inside the Berk)-3.222 F(ele)-.1 E
3.223(yd)-.15 G 3.223(omain. But)-3.223 F .723(if the)3.223 F 3.223(yp)
-.15 G .723(rocess an)-3.223 F .405(address that is unkno)102 321 R .405
(wn, the)-.25 F 2.905(yc)-.15 G .405
(an pass it \231upstairs\232 for further e)-2.905 F 2.905
(xamination. Thus)-.15 F .405(as ne)2.905 F 2.905(wh)-.25 G .405
(osts are)-2.905 F .488(added only one host \(the domain master\))102
333 R/F2 10/Times-Italic@0 SF(must)2.989 E F1 .489
(be updated immediately; other hosts can be updated)2.989 F(as con)102
345 Q -.15(ve)-.4 G(nient.).15 E .583
(Ideally this name resolution process w)127 361.2 R .583
(ould be performed by a name serv)-.1 F .582(er \(e.g., [Su82b]\) to)
-.15 F -.2(avo)102 373.2 S .507(id unnecessary cop).2 F .507
(ying of the message.)-.1 F(Ho)5.507 E(we)-.25 E -.15(ve)-.25 G 1.307
-.4(r, i).15 H 3.007(nab).4 G .507(atch netw)-3.007 F .508
(ork such as UUCP this could)-.1 F(result in unnecessary delays.)102
385.2 Q F0 2.5(5. COMP)72 409.2 R(ARISON WITH DELIVERMAIL)-.74 E F2
(Sendmail)112 425.4 Q F1(is an outgro)2.5 E(wth of)-.25 E F2
(delivermail)2.5 E F1 5(.T)C(he primary dif)-5 E(ferences are:)-.25 E
12.5(\(1\) Con\214guration)92 441.6 R .573
(information is not compiled in.)3.073 F .572
(This change simpli\214es man)5.572 F 3.072(yo)-.15 G 3.072(ft)-3.072 G
.572(he problems of)-3.072 F(mo)118.66 453.6 Q(ving to other machines.)
-.15 E(It also allo)5 E(ws easy deb)-.25 E(ugging of ne)-.2 E 2.5(wm)
-.25 G(ailers.)-2.5 E 12.5(\(2\) Address)92 469.8 R .491
(parsing is more \215e)2.991 F 2.991(xible. F)-.15 F .491(or e)-.15 F
(xample,)-.15 E F2(delivermail)2.992 E F1 .492(only supported one g)
2.992 F(ate)-.05 E -.1(wa)-.25 G 2.992(yt).1 G 2.992(oa)-2.992 G -.15
(ny)-2.992 G(netw)118.66 481.8 Q(ork, whereas)-.1 E F2(sendmail)2.5 E F1
(can be sensiti)2.5 E .3 -.15(ve t)-.25 H 2.5(oh).15 G
(ost names and reroute to dif)-2.5 E(ferent g)-.25 E(ate)-.05 E -.1(wa)
-.25 G(ys.).1 E 12.5(\(3\) F)92 498 R(orw)-.15 E 2.878(arding and :include: features eliminate the requirement that the system alias \214le be)
-.1 F 1.073(writable by an)118.66 510 R 3.573(yu)-.15 G 1.073(ser \(or that an update program be written, or that the system administration)
-3.573 F(mak)118.66 522 Q 2.5(ea)-.1 G(ll changes\).)-2.5 E(\(4\))92
538.2 Q F2(Sendmail)15 E F1 .443(supports message batching across netw)
2.944 F .443(orks when a message is being sent to multiple)-.1 F
(recipients.)118.66 550.2 Q 12.5(\(5\) A)92 566.4 R 1.945
(mail queue is pro)4.445 F 1.946(vided in)-.15 F F2(sendmail.)4.446 E F1
1.946(Mail that cannot be deli)6.946 F -.15(ve)-.25 G 1.946
(red immediately b).15 F 1.946(ut can)-.2 F .439(potentially be deli)
118.66 578.4 R -.15(ve)-.25 G .438
(red later is stored in this queue for a later retry).15 F 5.438(.T)-.65
G .438(he queue also pro)-5.438 F .438(vides a)-.15 F -.2(bu)118.66
590.4 S -.25(ff).2 G .838(er ag).25 F .839(ainst system crashes; after the message has been collected it may be reliably redeli)
-.05 F(v-)-.25 E(ered e)118.66 602.4 Q -.15(ve)-.25 G 2.5(ni).15 G 2.5
(ft)-2.5 G(he system crashes during the initial deli)-2.5 E -.15(ve)-.25
G(ry).15 E(.)-.65 E(\(6\))92 618.6 Q F2(Sendmail)15 E F1 1.351
(uses the netw)3.851 F 1.351(orking support pro)-.1 F 1.351
(vided by 4.2BSD to pro)-.15 F 1.35(vide a direct interf)-.15 F 1.35
(ace net-)-.1 F -.1(wo)118.66 630.6 S .283(rks such as the ARP).1 F .284
(ANET and/or Ethernet using SMTP \(the Simple Mail T)-.92 F .284
(ransfer Protocol\))-.35 F -.15(ove)118.66 642.6 S 2.5(raT).15 G
(CP/IP connection.)-2.5 E F0 -1(Ve)72 756 S(rsion 8.2)1 E(USENIX \255 J)
130.475 E(an 83)-.15 E(Last Mod 11/27/1993)88.355 E EP
%%Page: 9 9
%%BeginPageSetup
BP
%%EndPageSetup
/F0 10/Times-Roman@0 SF(REFERENCES)264.105 132 Q([Crock)87 148.2 Q 56.73
(er77] Crock)-.1 F(er)-.1 E 3.535(,D)-.4 G 3.535(.H)-3.535 G 1.035(., V)
-3.535 F 1.035(ittal, J. J., Pogran, K. T)-.6 F 1.035
(., and Henderson, D. A. Jr)-.74 F(.,)-.55 E/F1 10/Times-Italic@0 SF
(Stan-)3.535 E(dar)195 160.2 Q 2.627(df)-.37 G .127(or the F)-2.627 F
.127(ormat of ARP)-1.05 F 2.627(AN)-.9 G .128(etwork T)-2.627 F -.2(ex)
-.92 G 2.628(tM).2 G(essa)-2.628 E -.1(ge)-.1 G(s.).1 E F0 .128
(RFC 733, NIC 41952.)5.128 F(In [Feinler78].)195 172.2 Q(No)5 E -.15(ve)
-.15 G(mber 1977.).15 E([Crock)87 188.4 Q 56.73(er82] Crock)-.1 F(er)-.1
E 4.272(,D)-.4 G 4.272(.H)-4.272 G(.,)-4.272 E F1(Standar)4.272 E 4.272
(df)-.37 G 1.772(or the F)-4.272 F 1.772(ormat of Arpa Internet T)-1.05
F -.2(ex)-.92 G 4.271(tM).2 G(essa)-4.271 E -.1(ge)-.1 G(s.).1 E F0 .025
(RFC 822.)195 200.4 R(Netw)5.025 E .025(ork Information Center)-.1 F
2.526(,S)-.4 G .026(RI International, Menlo P)-2.526 F .026(ark, Cali-)
-.15 F 2.5(fornia. August)195 212.4 R(1982.)2.5 E 60.51
([Feinler78] Feinler)87 228.6 R 2.938(,E)-.4 G .438(., and Postel, J.)
-2.938 F(\(eds.\),)5.438 E F1(ARP)2.938 E .438(ANET Pr)-.9 F .438
(otocol Handbook.)-.45 F F0 .438(NIC 7104,)5.438 F(Netw)195 240.6 Q
3.011(ork Information Center)-.1 F 5.511(,S)-.4 G 3.012
(RI International, Menlo P)-5.511 F 3.012(ark, California.)-.15 F(1978.)
195 252.6 Q([No)87 268.8 Q 59.65(witz78] No)-.25 F .479
(witz, D. A., and Lesk, M. E.,)-.25 F F1 2.978(AD)2.978 G .478
(ial-Up Network of UNIX Systems.)-2.978 F F0(Bell)5.478 E 3.528
(Laboratories. In)195 280.8 R 1.029(UNIX Programmer')3.528 F 3.529(sM)
-.55 G 1.029(anual, Se)-3.529 F -.15(ve)-.25 G 1.029(nth Edition, V).15
F 1.029(olume 2.)-1.29 F(August, 1978.)195 292.8 Q 55.5
([Schmidt79] Schmidt,)87 309 R(E.,)2.631 E F1 .131(An Intr)2.631 F .131
(oduction to the Berk)-.45 F(ele)-.1 E 2.631(yN)-.3 G(etwork.)-2.631 E
F0(Uni)5.131 E -.15(ve)-.25 G .131(rsity of Califor).15 F(-)-.2 E
(nia, Berk)195 321 Q(ele)-.1 E 2.5(yC)-.15 G 2.5(alifornia. 1979.)-2.5 F
59.95([Shoens79] Shoens,)87 337.2 R(K.,)3.227 E F1 .728(Mail Refer)3.227
F .728(ence Manual.)-.37 F F0(Uni)5.728 E -.15(ve)-.25 G .728
(rsity of California, Berk).15 F(ele)-.1 E 4.528 -.65(y. I)-.15 H(n).65
E 3.478(UNIX Programmer')195 349.2 R 5.977(sM)-.55 G 3.477(anual, Se)
-5.977 F -.15(ve)-.25 G 3.477(nth Edition, V).15 F 3.477(olume 2C.)-1.29
F(December)8.477 E(1979.)195 361.2 Q 52.72([Solomon81] Solomon,)87 377.4
R .251(M., Landweber)2.75 F 2.751(,L)-.4 G .251(., and Neuhengen, D.,)
-2.751 F F1 .251(The Design of the CSNET)2.751 F .397(Name Server)195
389.4 R(.)-1.11 E F0 2.896(CS-DN-2. Uni)5.397 F -.15(ve)-.25 G .396
(rsity of W).15 F .396(isconsin, Madison.)-.4 F .396(October 1981.)5.396
F 73.84([Su82a] Su,)87 405.6 R(Za)2.844 E .344(w-Sing, and Postel, Jon,)
-.15 F F1 .344(The Domain Naming Con)2.844 F .344(vention for Internet)
-.4 F 2.71(User Applications.)195 417.6 R F0 5.21(RFC819. Netw)7.71 F
2.71(ork Information Center)-.1 F 5.21(,S)-.4 G 2.71(RI Interna-)-5.21 F
(tional, Menlo P)195 429.6 Q(ark, California.)-.15 E(August 1982.)5 E
73.28([Su82b] Su,)87 445.8 R(Za)4.174 E(w-Sing,)-.15 E F1 4.174(AD)4.174
G(istrib)-4.174 E 1.675(uted System for Internet Name Service)-.2 F(.)
-.15 E F0(RFC830.)6.675 E(Netw)195 457.8 Q 3.012(ork Information Center)
-.1 F 5.512(,S)-.4 G 3.011(RI International, Menlo P)-5.512 F 3.011
(ark, California.)-.15 F(October 1982.)195 469.8 Q/F2 10/Times-Bold@0 SF
(Mail Systems and Addr)72 756 Q(essing in 4.2bsd)-.18 E(9)259.93 E EP
%%Trailer
end
%%EOF