NAME¶
dot-qmail - control the delivery of mail messages
DESCRIPTION¶
Normally the
qmail-local program delivers each incoming message to your
system mailbox,
homedir/Mailbox, where
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.
THE QMAIL FILE¶
To change
qmail-local's behavior, set up a
.qmail file in your
home directory.
.qmail contains one or more lines. Each line is a delivery instruction.
qmail-local follows each instruction in turn. There are five types of
delivery instructions: (1) comment; (2) program; (3) forward; (4) mbox; (5)
maildir.
- (1)
- A comment line begins with a number sign:
# this is a comment
qmail-local ignores the line.
- (2)
- A program line begins with a vertical bar:
|preline /usr/ucb/vacation djb
qmail-local takes the rest of the line as a command to supply to
sh. See qmail-command(8) for further information.
- (3)
- A forward line begins with an ampersand:
&me@new.job.com
qmail-local takes the rest of the line as a mail address; it uses
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:
# the following examples are WRONG
&me@new
&<me@new.job.com>
& me@new.job.com
&me@new.job.com (New Address)
If the address begins with a letter or number, you may leave out the
ampersand:
me@new.job.com
Note that qmail-local omits its new Return-Path line when
forwarding messages.
- (4)
- An mbox line begins with a slash or dot, and does not end with a
slash:
/home/djb/Mailbox.sos
qmail-local takes the entire line as a filename. It appends the mail
message to that file, using flock-style file locking if possible.
qmail-local stores the mail message in mbox format, as
described in mbox(5).
WARNING: On many systems, anyone who can read a file can flock
it, and thus hold up qmail-local's delivery forever. Do not deliver
mail to a publicly accessible file!
If 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.
- (5)
- A maildir line begins with a slash or dot, and ends with a slash:
/home/djb/Maildir/
qmail-local takes the entire line as the name of a directory in
maildir format. It reliably stores the incoming message in that
directory. See maildir(5) for more details.
If
.qmail has the execute bit set, it must not contain any program lines,
mbox lines, or
maildir lines. If
qmail-local sees any
such lines, it will stop and indicate a temporary failure.
If
.qmail is completely empty (0 bytes long), or does not exist,
qmail-local follows the
defaultdelivery instructions set by your
system administrator; normally
defaultdelivery is
./Mailbox, so
qmail-local appends the mail message to
Mailbox in
mbox
format.
.qmail may contain extra spaces and tabs at the end of a line. Blank
lines are allowed, but not for the first line of
.qmail.
If
.qmail is world-writable,
qmail-local stops and indicates a
temporary failure.
SAFE QMAIL EDITING¶
Incoming messages can arrive at any moment. If you want to safely edit your
.qmail file, first set the sticky bit on your home directory:
chmod +t $HOME
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
chmod -t $HOME
when you are done! It's a good idea to test your new
.qmail file as
follows:
qmail-local -n $USER ~ $USER '' '' '' '' ./Mailbox
EXTENSION ADDRESSES¶
In the
qmail system, you control all local addresses of the form
user-anything, as well as the address
user itself, where
user is your account name. Delivery to
user -anything is controlled by the file
homedir/ .qmail-anything. (These rules may be
changed by the system administrator; see qmail-users(5).)
The
alias user controls all other addresses. Delivery to
local is
controlled by the file
homedir/.qmail-local,
where homedir is
alias's home directory.
In the following description,
qmail-local is handling a message addressed
to
local@domain, where
local is controlled by
.qmail-ext. Here is what it does.
If
.qmail-ext is completely empty, qmail-local
follows the
defaultdelivery instructions set by your system
administrator.
If
.qmail-ext doesn't exist, qmail-local will try
some default
.qmail files. For example, if
ext is
foo-bar,
qmail-local will try first
.qmail-foo-bar, then
.qmail-foo-default, and finally
.qmail-default. If none of these
exist,
qmail-local will bounce the message. (Exception: for the basic
user address,
qmail-local treats a nonexistent
.qmail the
same as an empty
.qmail.)
WARNING: For security,
qmail-local replaces any dots in
ext
with colons before checking
.qmail-ext. For
convenience, qmail-local converts any uppercase letters in
ext to lowercase.
When
qmail-local forwards a message as instructed in
.qmail-ext (or .qmail-default), it checks whether
.qmail-ext-owner exists. If so,
it uses local-owner@domain as the envelope
sender for the forwarded message. Otherwise it retains the envelope
sender of the original message. Exception: qmail-local
always retains the original envelope sender if it is the empty address or
#@[], i.e., if this is a bounce message.
qmail-local also supports
variable envelope return paths (VERPs):
if
.qmail-ext-owner and
.qmail-ext -owner-default both exist, it
uses local-owner-@domain-@[] as the
envelope sender. This will cause a recipient
recip@reciphost to see an envelope sender of
local
-owner-recip=reciphost@domain.
ERROR HANDLING¶
If a delivery instruction fails,
qmail-local stops immediately and
reports failure.
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,
qmail-local ignores all succeeding
lines in
.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
.qmail-ext file, and set up a central
.qmail file that forwards to all of the
.qmail-exts. Note that qmail-local can
handle any number of forward lines simultaneously.
SEE ALSO¶
envelopes(5),
maildir(5),
mbox(5),
qmail-users(5),
qmail-local(8),
qmail-command(8),
qmail-queue(8),
qmail-lspawn(8)