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on the filesystem on which the queue is mounted
the SMTP server will reject mail
with the
452 error code.
This invites the SMTP client to try again later.
.pp
Beware of setting this option too high;
it can cause rejection of email
when that mail would be processed without difficulty.
.pp
This option can also specify an advertised
.q "maximum message size"
for hosts that speak ESMTP.
.sh 2 "Privacy Flags"
.pp
The
.b p
option allows you to set certain
``privacy''
flags.
Actually, many of them don't give you any extra privacy,
rather just insisting that client SMTP servers
use the HELO command
before using certain commands.
.pp
The option takes a series of flag names;
the final privacy is the inclusive or of those flags.
For example:
.(b
Op needmailhelo, noexpn
.)b
insists that the HELO or EHLO command be used before a MAIL command is accepted
and disables the EXPN command.
.pp
The
.q restrictmailq
option restricts printing the queue to the group that owns the queue directory.
It is absurd to set this if you don't also protect the logs.
.pp
The
.q restrictqrun
option restricts people running the queue
(that is, using the
.b \-q
command line flag)
to root and the owner of the queue directory.
.sh 2 "Send to Me Too"
.pp
Normally,
.i sendmail
deletes the (envelope) sender from any list expansions.
For example, if
.q matt
sends to a list that contains
.q matt
as one of the members he won't get a copy of the message.
If the
.b \-m
(me too)
command line flag, or if the
.b m
option is set in the configuration file,
this behaviour is supressed.
Some sites like to run the
.sm SMTP
daemon with
.b \-m .
.sh 1 "THE WHOLE SCOOP ON THE CONFIGURATION FILE"
.pp
This section describes the configuration file
in detail,
including hints on how to write one of your own
if you have to.
.pp
There is one point that should be made clear immediately:
the syntax of the configuration file
is designed to be reasonably easy to parse,
since this is done every time
.i sendmail
starts up,
rather than easy for a human to read or write.
On the
.q "future project"
list is a
configuration-file compiler.
.pp
An overview of the configuration file
is given first,
followed by details of the semantics.
.sh 2 "Configuration File Lines"
.pp
The configuration file is organized as a series of lines,
each of which begins with a single character
defining the semantics for the rest of the line.
Lines beginning with a space or a tab
are continuation lines
(although the semantics are not well defined in many places).
Blank lines and lines beginning with a sharp symbol
(`#')
are comments.
.sh 3 "R and S \*- rewriting rules"
.pp
The core of address parsing
are the rewriting rules.
These are an ordered production system.
.i Sendmail
scans through the set of rewriting rules
looking for a match on the left hand side
(LHS)
of the rule.
When a rule matches,
the address is replaced by the right hand side
(RHS)
of the rule.
.pp
There are several sets of rewriting rules.
Some of the rewriting sets are used internally
and must have specific semantics.
Other rewriting sets
do not have specifically assigned semantics,
and may be referenced by the mailer definitions
or by other rewriting sets.
.pp
The syntax of these two commands are:
.(b F
.b S \c
.i n
.)b
Sets the current ruleset being collected to
.i n .
If you begin a ruleset more than once
it deletes the old definition.
.(b F
.b R \c
.i lhs
.i rhs
.i comments
.)b
The
fields must be separated
by at least one tab character;
there may be embedded spaces
in the fields.
The
.i lhs
is a pattern that is applied to the input.
If it matches,
the input is rewritten to the
.i rhs .
The
.i comments
are ignored.
.pp
Macro expansions of the form
.b $ \c
.i x
are performed when the configuration file is read.
Expansions of the form
.b $& \c
.i x
are performed at run time using a somewhat less general algorithm.
This for is intended only for referencing internally defined macros
such as
.b $h
that are changed at runtime.
.sh 4 "The left hand side"
.pp
The left hand side of rewriting rules contains a pattern.
Normal words are simply matched directly.
Metasyntax is introduced using a dollar sign.
The metasymbols are:
.(b
.ta \w'\fB$=\fP\fIx\fP  'u
\fB$*\fP	Match zero or more tokens
\fB$+\fP	Match one or more tokens
\fB$\-\fP	Match exactly one token
\fB$=\fP\fIx\fP	Match any phrase in class \fIx\fP
\fB$~\fP\fIx\fP	Match any word not in class \fIx\fP
.)b
If any of these match,
they are assigned to the symbol
.b $ \c
.i n
for replacement on the right hand side,
where
.i n
is the index in the LHS.
For example,
if the LHS:
.(b
$\-:$+
.)b
is applied to the input:
.(b
UCBARPA:eric
.)b
the rule will match, and the values passed to the RHS will be:
.(b
.ta 4n
$1	UCBARPA
$2	eric
.)b
.pp
Additionally, the LHS can include
.b $@
to match zero tokens.
This is
.i not
bound to a
.b $ \c
.i N
on the RHS, and is normally only used when it stands alone
in order to match the null input.
.sh 4 "The right hand side"
.pp
When the left hand side of a rewriting rule matches,
the input is deleted and replaced by the right hand side.
Tokens are copied directly from the RHS
unless they begin with a dollar sign.
Metasymbols are:
.(b
.ta \w'$#mailer\0\0\0'u
\fB$\fP\fIn\fP	Substitute indefinite token \fIn\fP from LHS
\fB$[\fP\fIname\fP\fB$]\fP	Canonicalize \fIname\fP
\fB$(\fP\fImap key\fP \fB$@\fP\fIarguments\fP \fB$:\fP\fIdefault\fP \fB$)\fP
	Generalized keyed mapping function
\fB$>\fP\fIn\fP	\*(lqCall\*(rq ruleset \fIn\fP
\fB$#\fP\fImailer\fP	Resolve to \fImailer\fP
\fB$@\fP\fIhost\fP	Specify \fIhost\fP
\fB$:\fP\fIuser\fP	Specify \fIuser\fP
.)b
.pp
The
.b $ \c
.i n
syntax substitutes the corresponding value from a
.b $+ ,
.b $\- ,
.b $* ,
.b $= ,
or
.b $~
match on the LHS.
It may be used anywhere.
.pp
A host name enclosed between
.b $[
and
.b $]
is looked up using the
.i gethostent \|(3)
routines and replaced by the canonical name\**.
.(f
\**This is actually
completely equivalent
to $(host \fIhostname\fP$).
In particular, a
.b $:
default can be used.
.)f
For example,
.q $[csam$]
might become
.q lbl-csam.arpa
and
.q $[[128.32.130.2]$]
would become
.q vangogh.CS.Berkeley.EDU.
.i Sendmail
recognizes it's numeric IP address
without calling the name server
and replaces it with it's canonical name.
.pp
The
.b $(
\&...
.b $)
syntax is a more general form of lookup;
it uses a named map instead of an implicit map.
If no lookup is found, the indicated
.i default
is inserted;
if no default is specified and no lookup matches,
the value is left unchanged.
.pp
The
.b $> \c
.i n
syntax
causes the remainder of the line to be substituted as usual
and then passed as the argument to ruleset
.i n .
The final value of ruleset
.i n
then becomes
the substitution for this rule.
.pp
The
.b $#
syntax should
.i only
be used in ruleset zero
or a subroutine of ruleset zero.
It causes evaluation of the ruleset to terminate immediately,
and signals to
.i sendmail
that the address has completely resolved.
The complete syntax is:
.(b
\fB$#\fP\fImailer\fP \fB$@\fP\fIhost\fP \fB$:\fP\fIuser\fP
.)b
This specifies the
{mailer, host, user}
3-tuple necessary to direct the mailer.
If the mailer is local
the host part may be omitted\**.
.(f
\**You may want to use it for special
.q "per user"
extensions.
For example, at CMU you can send email to
.q jgm+foo ;
the part after the plus sign
is not part of the user name,
and is passed to the local mailer for local use.
.)f
The
.i mailer
must be a single word,
but the
.i host
and
.i user
may be multi-part.
If the
.i mailer
is the builtin IPC mailer,
the
.i host
may be a colon-separated list of hosts
that are searched in order for the first working address
(exactly like MX records).
The
.i user
is later rewritten by the mailer-specific envelope rewriting set
and assigned to the
.b $u
macro.
As a special case, if the value to
.b $#
is
.q local
and the first character of the
.b $:
value is
.q @ ,
the
.q @
is stripped off, and a flag is set in the address descriptor
that causes sendmail to not do ruleset 5 processing.
.pp
Normally, a rule that matches is retried,
that is,
the rule loops until it fails.
A RHS may also be preceded by a
.b $@
or a
.b $:
to change this behavior.
A
.b $@
prefix causes the ruleset to return with the remainder of the RHS
as the value.
A
.b $:
prefix causes the rule to terminate immediately,
but the ruleset to continue;
this can be used to avoid continued application of a rule.
The prefix is stripped before continuing.
.pp
The
.b $@
and
.b $:
prefixes may precede a
.b $>
spec;
for example:
.(b
.ta 8n
R$+	$: $>7 $1
.)b
matches anything,
passes that to ruleset seven,
and continues;
the
.b $:
is necessary to avoid an infinite loop.
.pp
Substitution occurs in the order described,
that is,
parameters from the LHS are substituted,
hostnames are canonicalized,
.q subroutines
are called,
and finally
.b $# ,
.b $@ ,
and
.b $:
are processed.
.sh 4 "Semantics of rewriting rule sets"
.pp
There are five rewriting sets
that have specific semantics.
These are related as depicted by figure 2.
.(z
.hl
.ie n \{\
.(c
                    +---+
                 -->| 0 |-->resolved address
                /   +---+
               /            +---+   +---+
              /        ---->| 1 |-->| S |--
       +---+ / +---+  /     +---+   +---+  \e    +---+
addr-->| 3 |-->| D |--                      --->| 4 |-->msg
       +---+   +---+  \e     +---+   +---+  /    +---+
                        --->| 2 |-->| R |--
                            +---+   +---+
.)c

.\}
.el .ie !"\*(.T"" \
\{\
.PS
boxwid = 0.3i
boxht = 0.3i
movewid = 0.3i
moveht = 0.3i
linewid = 0.3i
lineht = 0.3i

	box invis "addr"; arrow
Box3:	box "3"
A1:	arrow
BoxD:	box "D"; line; L1: Here
C:	[
	C1:	arrow; box "1"; arrow; box "S"; line; E1: Here
		move to C1 down 0.5; right
	C2:	arrow; box "2"; arrow; box "R"; line; E2: Here
	] with .w at L1 + (0.5, 0)
	move to C.e right 0.5
L4:	arrow; box "4"; arrow; box invis "msg"
	line from L1 to C.C1
	line from L1 to C.C2
	line from C.E1 to L4
	line from C.E2 to L4
	move to BoxD.n up 0.6; right
Box0:	arrow; box "0"
	arrow; box invis "resolved address" width 1.3
	line from 1/3 of the way between A1 and BoxD.w to Box0
.PE
.\}
.el .sp 2i
.ce
Figure 2 \*- Rewriting set semantics
.(c
D \*- sender domain addition
S \*- mailer-specific sender rewriting
R \*- mailer-specific recipient rewriting
.)c
.hl
.)z
.pp
Ruleset three
should turn the address into
.q "canonical form."
This form should have the basic syntax:
.(b
local-part@host-domain-spec
.)b
If no
.q @
sign is specified,
then the
host-domain-spec
.i may
be appended from the
sender address
(if the
.b C
flag is set in the mailer definition
corresponding to the
.i sending
mailer).
Ruleset three
is applied by
.i sendmail
before doing anything with any address.
.pp
Ruleset zero
is applied after ruleset three
to addresses that are going to actually specify recipients.
It must resolve to a
.i "{mailer, host, user}"
triple.
The
.i mailer
must be defined in the mailer definitions
from the configuration file.
The
.i host
is defined into the
.b $h
macro
for use in the argv expansion of the specified mailer.
.pp
Rulesets one and two
are applied to all sender and recipient addresses respectively.
They are applied before any specification
in the mailer definition.
They must never resolve.
.pp
Ruleset four is applied to all addresses
in the message.
It is typically used
to translate internal to external form.
.sh 4 "IPC maile