SLOCAL(1)SLOCAL(1)NAMEslocal - asynchronously filter and deliver new mail
SYNOPSIS
/usr/contrib/mh/lib/slocal [address info sender]
[-addr address] [-info data] [-sender sender]
[-user username] [-mailbox mbox] [-file file]
[-maildelivery deliveryfile] [-verbose] [-noverbose]
[-suppressdup] [-nosuppressdup] [-debug]
[-version] [-help]
DESCRIPTION
Slocal is a program designed to allow you to have your
inbound mail processed according to a complex set of
selection criteria. You do not normally invoke slocal
yourself, rather slocal is invoked on your behalf by your
system's Message Transfer Agent (such as sendmail) when
the message arrives.
The message selection criteria used by slocal is specified
in the file .maildelivery in the user's home directory.
You can specify an alternate file with the `-maildelivery
file' option. The syntax of this file is specified below.
The message delivery address and message sender are deter-
mined from the Message Transfer Agent envelope informa-
tion, if possible. Under sendmail, the sender will
obtained from the UUCP "From " line, if present. The user
may override these values with command line arguments, or
arguments to the `-addr' and `-sender' switches.
The message is normally read from the standard input. The
`-file' switch sets the name of the file from which the
message should be read, instead of reading stdin. This is
useful when debugging a .maildelivery file.
The `-user' switch tells slocal the name of the user for
whom it is delivering mail. The `-mailbox' switch tells
slocal the name of the user's maildrop file.
slocal is able to detect and suppress duplicate messages.
To enable this, use the option `-suppressdup'. slocal
will keep a database containing the Message-ID's of incom-
ing messages, in order to detect duplicates. Depending on
your configuration, this database will be in either ndbm
or Berkeley db format.
The `-info' switch may be used to pass an arbitrary argu-
ment to sub-processes which slocal may invoke on your
behalf.
The `-verbose' switch causes slocal to give information on
stdout about its progress. The `-debug' switch produces
more verbose debugging output on stderr. These flags are
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useful when creating and debugging your .maildelivery
file, as they allow you to see the decisions and actions
that slocal is taking, as well as check for syntax errors
in your .maildelivery file.
Message Transfer Agents
If your MTA is sendmail, you should include the line
"| /usr/contrib/mh/lib/slocal -user username"
in your .forward file in your home directory. This will
cause sendmail to invoke slocal on your behalf when a mes-
sage arrives.
If your MTA is MMDF-I, you should (symbolically) link
/usr/contrib/mh/lib/slocal to the file bin/rcvmail in your
home directory. This will cause MMDF-I to invoke slocal
on your behalf with the correct "address info sender"
arguments.
If your MTA is MMDF-II, then you should not use slocal.
An equivalent functionality is already provided by MMDF-
II; see maildelivery(5) for details.
The Maildelivery File
The .maildelivery file controls how slocal filters and
delivers incoming mail. Each line of this file consists
of five fields, separated by white-space or comma. Since
double-quotes are honored, these characters may be
included in a single argument by enclosing the entire
argument in double-quotes. A double-quote can be included
by preceding it with a backslash. Lines beginning with
`#' and blank lines are ignored.
The format of each line in the .maildelivery file is:
header pattern action result string
header:
The name of a header field (such as To, Cc, or From)
that is to be searched for a pattern. This is any
field in the headers of the message that might be
present.
The following special fields are also defined:
source the out-of-band sender information
addr the address that was used to cause delivery
to the recipient
default this matches only if the message hasn't
been delivered yet
* this always matches
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SLOCAL(1)SLOCAL(1)
pattern:
The sequence of characters to match in the specified
header field. Matching is case-insensitive, but does
not use regular expressions.
action:
The action to take to deliver the message. When a
message is delivered, a "Delivery-Date: date" header
is added which indicates the date and time that mes-
sage was delivered.
destroy This action always succeeds.
file, mbox, or > Append the message to the file named
by string. The message is appended to the
file in mbox (uucp) format. This is the
format used by most other mail clients
(such as mailx, elm). If the message can
be appended to the file, then this action
succeeds.
mmdf Identical to file, but always appends the
message using the MMDF mailbox format.
pipe or | Pipe the message as the standard input to
the command named by string, using the
Bourne shell sh(1) to interpret the string.
Prior to giving the string to the shell, it
is expanded with the following built-in
variables:
$(sender) the out-of-band sender informa-
tion
$(address) the address that was used to
cause delivery to the recipient
$(size) the size of the message in bytes
$(reply-to) either the "Reply-To:" or
"From:" field of the message
$(info) the out-of-band information spec-
ified
qpipe or <caret> Similar to pipe, but executes the
command directly, after built-in variable
expansion, without assistance from the
shell. This action can be used to avoid
quoting special characters which your shell
might interpret.
folder or + Store the message in the nmh folder named
by string. Currently his is handled by
piping the message to the nmh program `rcv-
store', although this may change in the
future.
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result:
Indicates how the action should be performed:
A Perform the action. If the action suc-
ceeds, then the message is considered
delivered.
R Perform the action. Regardless of the out-
come of the action, the message is not con-
sidered delivered.
? Perform the action only if the message has
not been delivered. If the action suc-
ceeds, then the message is considered
delivered.
N Perform the action only if the message has
not been delivered and the previous action
succeeded. If this action succeeds, then
the message is considered delivered.
The delivery file is always read completely, so that sev-
eral matches can be made and several actions can be taken.
Security of Delivery Files
In order to prevent security problems, the .maildelivery
file must be owned either by the user or by root, and must
be writable only by the owner. If this is not the case,
the file is not read.
If the .maildelivery file cannot be found, or does not
perform an action which delivers the message, then slocal
will check for a global delivery file at /usr/con-
trib/mh/etc/maildelivery. This file is read according to
the same rules. This file must be owned by the root and
must be writable only by the root.
If a global delivery file cannot be found or does not per-
form an action which delivers the message, then standard
delivery to the user's maildrop is performed.
Example Delivery File
To summarize, here's an example delivery file:
#
# .maildelivery file for nmh's slocal
#
# Blank lines and lines beginning with a '#' are ignored
#
# FIELD PATTERN ACTION RESULT STRING
#
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# File mail with foobar in the "To:" line into file foobar.log
To foobar file A foobar.log
# Pipe messages from coleman to the program message-archive
From coleman pipe A /bin/message-archive
# Anything to the "nmh-workers" mailing list is put in
# its own folder, if not filed already
To nmh-workers folder ? nmh-workers
# Anything with Unix in the subject is put into
# the file unix-mail
Subject unix file A unix-mail
# I don't want to read mail from Steve, so destroy it
From steve destroy A -
# Put anything not matched yet into mailbox
default - file ? mailbox
# always run rcvtty
* - pipe R /nmh/lib/rcvtty
Sub-process environment
When a process is invoked, its environment is: the
user/group-ids are set to recipient's ids; the working
directory is the recipient's home directory; the umask is
0077; the process has no /dev/tty; the standard input is
set to the message; the standard output and diagnostic
output are set to /dev/null; all other file-descriptors
are closed; the environment variables $USER, $HOME, $SHELL
are set appropriately, and no other environment variables
exist.
The process is given a certain amount of time to execute.
If the process does not exit within this limit, the pro-
cess will be terminated with extreme prejudice. The
amount of time is calculated as ((size / 60) + 300) sec-
onds, where size is the number of bytes in the message
(with 30 minutes the maximum time allowed).
The exit status of the process is consulted in determining
the success of the action. An exit status of zero means
that the action succeeded. Any other exit status (or
abnormal termination) means that the action failed.
In order to avoid any time limitations, you might imple-
ment a process that began by forking. The parent would
return the appropriate value immediately, and the child
could continue on, doing whatever it wanted for as long as
it wanted. This approach is somewhat risky if the parent
is going to return an exit status of zero. If the parent
is going to return a non-zero exit status, then this
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approach can lead to quicker delivery into your maildrop.
FILES
/usr/contrib/mh/etc/mts.conf nmh mts configuration file
$HOME/.maildelivery The file controlling local delivery
/usr/contrib/mh/etc/maildelivery Rather than the standard file
/var/mail/$USER The default maildrop
SEE ALSOrcvdist(1), rcvpack(1), rcvstore(1), rcvtty(1), mh-for-
mat(5)DEFAULTS
`-noverbose'
`-nosuppressdup'
`-maildelivery .maildelivery'
`-mailbox /var/mail/$USER'
`-file' defaults to stdin
`-user' defaults to the current user
CONTEXT
None
HISTORY
Slocal was originally designed to be backward-compatible
with the maildelivery facility provided by MMDF-II. Thus,
the .maildelivery file syntax is somewhat limited. But
slocal has been modified and extended, so that is it no
longer compatible with MMDF-II.
In addition to an exit status of zero, the MMDF values
RP_MOK (32) and RP_OK (9) mean that the message has been
fully delivered. Any other non-zero exit status, includ-
ing abnormal termination, is interpreted as the MMDF value
RP_MECH (200), which means "use an alternate route"
(deliver the message to the maildrop).
BUGS
Only two return codes are meaningful, others should be.
Slocal was originally designed to be backwards-compatible
with the maildelivery functionality provided by MMDF-II.
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