debian/rules: Use `git' potty wrapper.

[qmail] / dot-qmail.9

.TH dot-qmail 5
.SH NAME
dot-qmail \- control the delivery of mail messages
.SH DESCRIPTION
Normally the
.B qmail-local
program delivers each incoming message to your system mailbox,
.IR homedir\fB/Mailbox ,
where
.I homedir
is your home directory.

It can instead
write the mail to a different file or directory,
forward it to another address,
distribute it to a mailing list,
or even execute programs,
all under your control.
.SH "THE QMAIL FILE"
To change
.BR qmail-local 's
behavior, set up a
.B .qmail
file in your home directory.

.B .qmail
contains one or more lines.
Each line is a delivery instruction.
.B qmail-local
follows each instruction in turn.
There are five types of delivery instructions:
(1) comment; (2) program; (3) forward; (4) mbox; (5) maildir.
.TP 5
(1)
A comment line begins with a number sign:

.EX
     # this is a comment
.EE

.B qmail-local
ignores the line.  However,
.BR qmail-valid-addresses (8)
interprets some markers in comments.  If the first line of a
.B .qmail
file begins `#!' then the address (or addresses) controlled by the file
are considered invalid, and any attempt to send to them is refused by
.BR qmail-smtpd (8).
(Note: This doesn't prevent local users sending mail directly.  This
feature can therefore be used to experiment with mail rules before
allowing the entire Internet to break them.)  If the first line of a
.B .qmail
file begins `#?' then 
.BR qmail-smtpd (8)
will consult a Userv service
.BI addrcheck: ext
to decide whether addresses matched by the extension
.I ext
are valid.  The service is passed many arguments, though the first two
are the most interesting.  The first is the local-part tail (i.e., the
bit that matched
.BR default )
and the second is the envelope sender.
.TP 5
(2)
A program line begins with a vertical bar:

.EX
     |preline /usr/ucb/vacation djb
.EE

.B qmail-local
takes the rest of the line as a command to supply to
.BR sh .
See
.B qmail-command(8)
for further information.
.TP 5
(3)
A forward line begins with an ampersand:

.EX
     &me@new.job.com
.EE

.B qmail-local
takes the rest of the line as a mail address;
it uses
.B qmail-queue
to forward the message to that address.
The address must contain a fully qualified domain name;
it must not contain extra spaces, angle brackets, or comments:

.EX
     # the following examples are WRONG
.br
     &me@new
.br
     &<me@new.job.com>
.br
     & me@new.job.com
.br
     &me@new.job.com (New Address)
.EE

If the address begins with a letter or number,
you may leave out the ampersand:

.EX
     me@new.job.com
.EE

Note that
.B qmail-local
omits its new
.B Return-Path
line when forwarding messages.
.TP 5
(4)
An 
.I mbox
line begins with a slash or dot,
and does not end with a slash:

.EX
     /home/djb/Mailbox.sos
.EE

.B qmail-local
takes the entire line as a filename.
It appends the mail message to that file,
using
.BR flock -style
file locking if possible.
.B qmail-local
stores the mail message in
.I mbox
format, as described in
.BR mbox(5) .

.B WARNING:
On many systems,
anyone who can read a file can
.B flock
it, and thus hold up
.BR qmail-local 's
delivery forever.
Do not deliver mail to a publicly accessible file!

If
.B qmail-local
is able to lock the file, but has trouble writing to it
(because, for example, the disk is full),
it will truncate the file back to its original length.
However, it cannot prevent mailbox corruption if the system
crashes during delivery.
.TP 5
(5)
A
.I maildir
line begins with a slash or dot,
and ends with a slash:

.EX
     /home/djb/Maildir/
.EE

.B qmail-local
takes the entire line as the name of a directory in
.I maildir
format.
It reliably stores the incoming message in that directory.
See
.B maildir(5)
for more details.
.TP 5
(6)
An
.I sender
line begins with a less-than-sign `<'.  The remainder of the line is set
as the new envelope sender for any forwarding done through this file.
.TP 5
(7)
An
.I environment
line begins with an exclamation mark `!'.  If the remainder of the line
has the form
.IB var = value
then the environment variable
.I var
is set to 
.I value
for the following program deliveries.  If there is no equals sign, the
named environment variable is deleted.
.PP
If
.B .qmail
has the execute bit set,
it must not contain any
program lines,
.I mbox
lines,
or
.I maildir
lines.
If
.B qmail-local
sees any such lines,
it will stop and indicate a temporary failure.

If
.B .qmail
is completely empty (0 bytes long), or does not exist,
.B qmail-local
follows the
.I defaultdelivery
instructions set by your system administrator;
normally
.I defaultdelivery
is
.BR ./Mailbox ,
so
.B qmail-local
appends the mail message to
.B Mailbox
in
.I mbox
format.

.B .qmail
may contain extra spaces and tabs at the end of a line.
Blank lines are allowed, but not for the first line of
.BR .qmail .

If
.B .qmail
is world-writable or group-writable,
.B qmail-local
stops and indicates a temporary failure.
.SH "SAFE QMAIL EDITING"
Incoming messages can arrive at any moment.
If you want to safely edit your
.B .qmail
file, first set the sticky bit on your home directory:

.EX
     chmod +t $HOME
.EE

.B qmail-local
will temporarily defer delivery of any message to you
if your home directory is sticky
(or group-writable or other-writable,
which should never happen).
Make sure to

.EX
     chmod -t $HOME
.EE

when you are done!
It's a good idea to test your new
.B .qmail
file as follows:

.EX
     qmail-local -n $USER ~ $USER '' '' '' '' ./Mailbox
.EE
.SH "EXTENSION ADDRESSES"
In the
.B qmail
system,
you control all local addresses of the form
.IR user\fBBREAK\fIanything ,
as well as the address
.I user
itself,
where
.I user
is your account name.
Delivery to
.I user\fBBREAK\fIanything
is controlled by the file
.IR homedir/\fB.qmail\-\fIanything .
(These rules may be changed by the system administrator;
see
.BR qmail-users (5).)

The
.B alias
user controls all other addresses.
Delivery to
.I local
is controlled by the file
.IR homedir/\fB.qmail\-\fIlocal ,
where
.I homedir
is
.BR alias 's
home directory.

In the following description,
.B qmail-local
is handling a message addressed to
.IR local@domain ,
where
.I local
is controlled by
.BR .qmail\-\fIext .
Here is what it does.

If
.B .qmail\-\fIext
is completely empty,
.B qmail-local
follows the
.I defaultdelivery
instructions set by your system administrator.

If
.B .qmail\-\fIext
doesn't exist,
.B qmail-local
will try some default
.B .qmail
files.
For example,
if
.I ext
is
.BR foo-bar ,
.B qmail-local
will try first
.BR .qmail-foo-bar ,
then
.BR .qmail-foo-default ,
and finally
.BR .qmail-default .
If none of these exist,
.B qmail-local
will bounce the message.
(Exception: for the basic
.I user
address,
.B qmail-local
treats a nonexistent
.B .qmail
the same as an empty
.BR .qmail .)

.B WARNING:
For security,
.B qmail-local
replaces any dots in
.I ext
with colons before checking
.BR .qmail\-\fIext .
For convenience,
.B qmail-local
converts any uppercase letters in
.I ext
to lowercase.

When
.B qmail-local
forwards a message as instructed in
.B .qmail\-\fIext
(or
.BR .qmail-default ),
it checks whether
.B .qmail\-\fIext\fB-owner\fP
exists.
If so,
it uses
.I local\fB-owner@\fIdomain
as the envelope sender for the forwarded message.
Otherwise it retains the envelope sender of the original message.
Exception:
.B qmail-local
always retains the original envelope sender
if it is the empty address or
.BR #@[] ,
i.e., if this is a bounce message.

.B qmail-local
also supports
.B variable envelope return paths
(VERPs):
if
.B .qmail\-\fIext\fB-owner\fP
and
.B .qmail\-\fIext\fB-owner-default\fP
both exist, it uses
.I local\fB\-owner\-@\fIdomain\fB-@[]
as the envelope sender.
This will cause a recipient
.I recip\fB@\fIreciphost
to see an envelope sender of
.IR local\fB\-owner\-\fIrecip\fB=\fIreciphost\fB@\fIdomain .
.SH "ERROR HANDLING"
If a delivery instruction fails,
.B qmail-local
stops immediately and reports failure.
.B qmail-local
handles forwarding after all other instructions,
so any error in another type of delivery will prevent all forwarding.

If a program returns exit code 99,
.B qmail-local
ignores all succeeding lines in
.BR .qmail ,
but it still pays attention to previous forward lines.

To set up independent instructions,
where a temporary or permanent failure in one instruction
does not affect the others,
move each instruction into a separate
.B .qmail\-\fIext
file, and set up a central
.B .qmail
file that forwards to all of the
.BR .qmail\-\fIext s.
Note that
.B qmail-local
can handle any number of forward lines simultaneously.
.SH "SEE ALSO"
envelopes(5),
maildir(5),
mbox(5),
qmail-users(5),
qmail-local(8),
qmail-command(8),
qmail-queue(8),
qmail-lspawn(8)