slocal - MH receive-mail hooks
slocal $HOME/.maildelivery [-form formfile] [switches for postproc]
/usr/lib/mh/rcvpack file [-help]
/usr/lib/mh/rcvtty [command...] [-help]
A receive-mail hook is a program that is run whenever you receive a mail
message. You do not invoke the hook yourself; it is invoked on your behalf
by sendmail, when you include the following line in your .forward file in
your home directory:
"| /usr/lib/mh/slocal -user username"
The .maildelivery file, which is an ordinary ASCII file, controls how local
delivery is performed. This file is read by slocal.
The format of each line in the .maildelivery file is:
field pattern action result string
These components are explained below:
The name of a field that is to be searched for a pattern. This is any
field in the headers of the message that might be present. In addition,
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 has not been delivered yet
*: this always matches
The sequence of characters to match in the specified field. Matching
is case-insensitive but not Regular Expression-based.
The action to take to deliver the message. This is one of the follow-
file or >:
Append the message to the file named by string using the standard
maildrop delivery process. If the message can be appended to the
file, then this action succeeds. When writing to the file, a new
field is added:
This field indicates the date and time at which the message was
appended to the file.
pipe or | :
Pipe the message as the standard input to the command named by
string. The Bourne shell, sh(1), is used to interpret the string.
Prior to giving the string to the shell, it is expanded with the
following built-in variables:
$(sender): the return address for the message
$(address): the address that was used to cause delivery to the
$(size): the size of the message in bytes
$(reply-to): either the Reply-To: or From: field of the message
$(info): miscellaneous out-of-band information
When a process is invoked, its environment is as follows: the
user/group id's are set to recipient's id's; the working directory
is the recipient's 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, and
$SHELL are set appropriately; 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, it is terminated. The
amount of time is calculated as ((size x 60) + 300) seconds, where
size is the number of bytes in the message.
The exit status of the process is consulted to determine the suc-
cess of the action. An exit status of 0 means that the action suc-
ceeded. Any other exit status (or abnormal termination) means that
the action failed.
In order to avoid any time limitations, you might implement a pro-
cess that began by forking. The parent would return the appropriate
value immediately, and the child could continue to do whatever it
wanted for as long as it wanted. This approach should only be used
if you do not care about the outcome of the action, because the
success or failure of the child process cannot be passed back to
slocal. However, if the parent is going to return a non-zero exit
status, then this approach can lead to quicker delivery into your
qpipe or ^ :
This is similar to pipe, but executes the command directly, after
built-in variable expansion, without assistance from the shell.
This action always succeeds.
Indicates how the action should be performed. The following values are
A: Perform the action. If the action succeeded, then the message is
R: Perform the action. Regardless of the outcome of the action, the
message is not considered delivered.
?: Perform the action only if the message has not been delivered. If
the action succeeded, then the message is considered delivered.
The file is always read completely, so that several matches can be made and
several actions can be taken. The .maildelivery file must be owned either
by the user or by root, and must be writable only by the owner. If the
.maildelivery file cannot be found, or does not perform an action which
delivers the message, then the file /usr/lib/mh/maildelivery is read
according to the same rules. This file must be owned by the root and must
be writable only by the root. If this file cannot be found or does not per-
form an action which delivers the message, then standard delivery to the
user's maildrop, /usr/spool/mail/$USER, is performed.
Arguments in the .maildelivery file are separated by a comma (,) or by
white space. 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 back-
Four programs are currently available: rcvdist redistributes incoming mes-
sages to additional recipients; rcvpack saves incoming messages in a
packf(1) file; and rcvtty notifies the user of incoming messages. The
fourth program, rcvstore, is described in the rcvstore(1) reference page.
They all reside in the /usr/lib/mh directory.
The rcvdist program resends a copy of the message to all of the addresses
listed on its command line. It uses the format string facility described in
The rcvpack program appends a copy of the message to the file listed on its
command line. It is made obsolete by .maildelivery.
The rcvtty program executes the named file with the message as its standard
input, and gives the resulting output to the terminal access daemon for
display on your terminal. If the terminal access daemon is unavailable on
your system, then rcvtty writes the output to your terminal, only if your
terminal has world-writable permission. If no valid file is specified, then
rcvtty gives a one-line scan listing to the terminal access daemon.
For compatibility with older versions of MH, if slocal cannot find the
user's .maildelivery file, it attempts to execute an old-style rcvmail hook
in the user's $HOME directory. Specifically, it first attempts to execute
.mh_receive file maildrop directory user
Failing that it attempts to execute:
$HOME/bin/rcvmail user file sender
If both of these fail, it gives up and write to the user's maildrop.
In addition, whenever a hook or process is invoked, file-descriptor three
(3) is set to the message in addition to the standard input.
Only two return codes are meaningful, others should be.
This section shows how slocal could be used.
In this example, line-by-line comments have been extracted from the code to
aid readability of the example. The line numbers would not normally be in
the code; they are there to help you. The code fragment precedes the expla-
field pattern action result string
(1) To mmdf2 file A mmdf2.log
(2) From mmdf pipe A
(3) Sender uk-mmdf file ? mmdf2.log
(4) To Unix > A unix-news
(5) addr jpo=mmdf | A mmdf-redist
(6) addr jpo=ack | R
(7) From steve destroy A -
(8) default - > ? mailbox
(9) * - | R rcvalert
File mail with mmdf2 in the To: line into file mmdf2.log.
Messages from mmdf are piped to the program err-message-archive.
Take anything with the address uk-mmdf in the Sender: field, and file
it in mmdf2.log, if it has not already been filed by line 1.
Put messages addressed to Unix in the file unix-news.
If the address is jpo=mmdf, pipe the message into mmdf-redist.
If the address is jpo=ack, send an acknowledgement copy back.
Destroy anything from steve.
Take anything that is not matched yet and put it into mailbox.
Always run rcvalert.
The system customization file.
The system default file controlling local delivery.
The user-supplied alternative to the system default file controlling