<html>
<head>
<title>The Exim FAQ Section 4</title>
</head>
<body bgcolor="#F8F8F8" text="#00005A" link="#FF6600" alink="#FF9933" vlink="#990000">
<h1>The Exim FAQ</h1>
<a href="FAQ.html#TOC">Contents</a>
<a href="FAQ_3.html">Previous</a>
<a href="FAQ_5.html">Next</a>
<hr><br>
<h2><a href="FAQ.html#TOC146">4. ROUTING FOR LOCAL DELIVERY</a></h2>
<p>
<a name="TOC147" href="FAQ.html#TOC147">Q0401:</a> I need to have any mail for <i>virt.dom.ain</i> that doesn't match one of the
aliases in <i>/usr/lib/aliases.virt</i> delivered to a particular address, for
example, <i>postmaster@virt.dom.ain</i>.
</p>
<p>
<font color="#00BB00">A0401:</font> Adding an asterisk to a search type causes Exim to look up “*” when the
normal lookup fails. So if your aliasing router is something like this:
</p>
<pre>
virtual:
driver = redirect
domains = virt.dom.ain
data = ${lookup{$local_part}lsearch{/usr/lib/aliases.virt}}
no_more</pre>
<p>
you should change <tt>lsearch</tt> to <tt>lsearch*</tt>, and put this in the alias
file:
</p>
<pre>
*: postmaster@virt.dom.ain</pre>
<p>
This solution has the feature that if there are several unknown
addresses in the same message, only one copy gets sent to the
postmaster, because of Exim's normal de-duplication rules.
</p>
<p>
NOTE: This solution works only if there is also an entry for <i>postmaster</i>
in the alias file, ultimately resolving to an address that is not in
<i>virt.dom.ain</i>. See also <a href="FAQ_4.html#TOC180">Q0434</a>.
</p>
<p>
<a name="TOC148" href="FAQ.html#TOC148">Q0402:</a> How do I arrange for all incoming email for <i>*@some.domain</i> to go into one
pop3 mail account? The customer doesn't want to add a list of specific
local parts to the system.
</p>
<p>
<font color="#00BB00">A0402:</font> Set up a special transport that writes to the mailbox like this:
</p>
<pre>
special_transport:
driver = appendfile
file = /pop/mailbox
envelope_to_add
return_path_add
delivery_date_add
user = exim</pre>
<p>
The file will be written as the user <tt>exim</tt>. Then arrange to route all
mail for that domain to that transport, with a router like this:
</p>
<pre>
special_router:
driver = accept
domains = some.domain
transport = special_transport</pre>
<p>
<a name="TOC149" href="FAQ.html#TOC149">Q0403:</a> How do I configure Exim to send messages for unknown local users to a
central server?
</p>
<p>
<font color="#00BB00">A0403:</font> Assuming you are using something like the default configuration, where
local users are processed by the later routers, you should add the
following router at the end:
</p>
<pre>
unknown:
driver = manualroute
transport = remote_smtp
route_list = * server.host.name
no_verify</pre>
<p>
However, you should if possible try to verify that the user is known on
the central server before accepting the message in the first place. This
can be done by making use of Exim's “call forward” facility.
</p>
<p>
<a name="TOC150" href="FAQ.html#TOC150">Q0404:</a> How can I arrange for messages submitted by (for example) Majordomo to
be handled specially?
</p>
<p>
<font color="#00BB00">A0404:</font> You can use the <tt>condition</tt> option on a router, with a setting such as
</p>
<pre>
condition = ${if and {{eq {$sender_host_address}{}} \
{eq {$sender_ident}{majordom}}} {yes}{no}}</pre>
<p>
This first tests for a locally-submitted message, by ensuring there is
no sending host address, and then it checks the identity of the user
that ran the submitting process.
</p>
<p>
<a name="TOC151" href="FAQ.html#TOC151">Q0405:</a> On a host that accepts mail for several domains, do I have to use fully
qualified addresses in <i>/etc/aliases</i> or do I have to set up an alias
file for each domain?
</p>
<p>
<font color="#00BB00">A0405:</font> You can do it either way. The default aliasing router contains this line:
</p>
<pre>
data = ${lookup{$local_part}lsearch{/etc/aliases}}</pre>
<p>
which is what does the actual lookup. To make it look up the complete
address instead of just the local part, use
</p>
<pre>
data = ${lookup{$local_part@$domain}lsearch{/etc/aliases}}</pre>
<p>
If you want to use a separate file for each domain, use
</p>
<pre>
data = ${lookup{$local_part}lsearch{/etc/aliases/$domain}}</pre>
<p>
<a name="TOC152" href="FAQ.html#TOC152">Q0406:</a> Some of my users are using the <i>.forward</i> to pipe to a shell command which
appends to the user's INBOX. How can I forbid this?
</p>
<p>
<font color="#00BB00">A0406:</font> If you allow your users to run shells in pipes, you cannot control which
commands they run or which files they write to. However, you should point
out to them that writing to an INBOX by arbitrary commands is not
interlocked with the MTA and MUAs, and is liable to mess up the contents
of the file.
</p>
<p>
If a user simply wants to choose a specific file for the delivery of
messages, this can be done by putting a file name in a <i>.forward</i> file
rather than using a pipe, or by using the <tt>save</tt> command in an Exim
filter file.
</p>
<p>
You can set <tt>forbid_pipe</tt> on the router, but that will prevent them from
running any pipe commands at all. Alternatively, you can restrict which
commands they may run in their pipes by setting the <tt>allow_commands</tt>
and/or <tt>restrict_to_path</tt> options in the <b>address_pipe</b> transport.
</p>
<p>
<a name="TOC153" href="FAQ.html#TOC153">Q0407:</a> How can I arrange for a default value when using a query-style lookup
such as LDAP or NIS+ to handle aliases?
</p>
<p>
<font color="#00BB00">A0407:</font> Use a second query in the failure part of the original lookup, like
this:
</p>
<pre>
data = ${lookup ldap\
{ldap://x.y.z/l=yvr?aliasaddress?sub?(&(mail=$local_part@$domain))}\
{$value}\
{\
${lookup ldap \
{ldap://x.y.z/l=yvr?aliasaddress?sub?(&(mail=default@$domain))}}\
}}</pre>
<p>
Of course, if the default is a fixed value you can just include it
directly.
</p>
<p>
<a name="TOC154" href="FAQ.html#TOC154">Q0408:</a> If I don't fully qualify the addresses in a virtual domain's alias file
then mail to aliases which also match the local domain get delivered to
the local domain.
</p>
<p>
<font color="#00BB00">A0408:</font> Set the <tt>qualify_preserve_domain</tt> option on the <b>redirect</b> router.
</p>
<p>
<a name="TOC155" href="FAQ.html#TOC155">Q0409:</a> I want mail for any local part at certain virtual domains to go
to a single address for each domain.
</p>
<p>
<font color="#00BB00">A0409:</font> One way to to this is
</p>
<pre>
virtual:
driver = redirect
data = ${lookup{$domain}lsearch{/etc/virtual}}</pre>
<p>
The <i>/etc/virtual</i> file contains a list of domains and the addresses to
which their mail should be sent. For example:
</p>
<pre>
domain1: postmaster@some.where.else
domain2: joe@xyz.plc</pre>
<p>
If the number of domains is large, using a DBM or cdb file would be more
efficient. If the lookup fails to find the domain in the file, the value
of the <tt>data</tt> option is empty, causing the router to decline.
</p>
<p>
<a name="TOC156" href="FAQ.html#TOC156">Q0410:</a> How can I make Exim look in the alias NIS map instead of <i>/etc/aliases</i>?
</p>
<p>
<font color="#00BB00">A0410:</font> The default configuration does not use NIS (many hosts don't run it).
You need to change this line in the <b>system_aliases</b> router:
</p>
<pre>
data = ${lookup{$local_part}lsearch{/etc/aliases}}</pre>
<p>
Change it to
</p>
<pre>
data = ${lookup{$local_part}nis{mail.aliases}}</pre>
<p>
If you want to use <i>/etc/aliases</i> as well as NIS, put this router (with
a different name) before or after the default one, depending on which
data source you want to take precedence.
</p>
<p>
<a name="TOC157" href="FAQ.html#TOC157">Q0411:</a> Why will Exim deliver a message locally to any username that is longer
than 8 characters as long as the first 8 characters match one of the
local usernames?
</p>
<p>
<font color="#00BB00">A0411:</font> The problem is in your operating system. Exim just calls the <i>getpwnam()</i>
function to test a local part for being a local login name. It does not
presume to guess the maximum length of user name for the underlying
operating system. Many operating systems correctly reject names that are
longer than the maximum length; yours is apparently deficient in this
regard. To cope with such systems, Exim has an option called
<tt>max_user_name_length</tt> which you can set to the maximum allowed length.
</p>
<p>
<a name="TOC158" href="FAQ.html#TOC158">Q0412:</a> Why am I seeing the error <i>bad mode (100664) for /home/test/.forward</i>?
I've looked through the documentation but can't see anything to suggest
that Exim has to do anything other than read the <i>.forward</i> file.
</p>
<p>
<font color="#00BB00">A0412:</font> For security, Exim checks for mode bits that shouldn't be set, by
default 022. You can change this by setting the <tt>modemask</tt> option of the
<b>redirect</b> router that is handling <i>.forward</i> files.
</p>
<p>
<a name="TOC159" href="FAQ.html#TOC159">Q0413:</a> When a user's <i>.forward</i> file is syntactially invalid, Exim defers
delivery of all messages to that user, which sometimes include the
user's own test messages. Can it be told to ignore the <i>.forward</i> file
and/or inform the user of the error?
</p>
<p>
<font color="#00BB00">A0413:</font> Setting <tt>skip_syntax_errors</tt> on the redirect router causes syntax
errors to be skipped. When dealing with users' <i>.forward</i> files it is best
to combine this with a setting of <tt>syntax_errors_to</tt> in order to send
a message about the error to the user. However, to avoid an infinite
cascade of messages, you have to be able to send to an address that
bypasses <i>.forward</i> file processing. This can be done by including a
router like this one
</p>
<pre>
real_localuser:
driver = accept
check_local_user
transport = local_delivery
prefix = real-</pre>
<p>
before the <b>redirect</b> router that handles <i>.forward</i> files. This will
do an ordinary local delivery without <i>.forward</i> processing, if the
local part is prefixed by <tt>real-</tt>. You can then set something like
the following options on the <b>redirect</b> router:
</p>
<pre>
skip_syntax_errors
syntax_errors_to = real-$local_part@$domain
syntax_errors_text = "\
This is an automatically generated message. An error has been \
found\nin your .forward file. Details of the error are reported \
below. While\nthis error persists, messages addressed to you will \
get delivered into\nyour normal mailbox and you will receive a \
copy of this message for\neach one."</pre>
<p>
A final tidying setting to go with this is a rewriting rule that changes
<tt>real-username</tt> into just <tt>username</tt> in the headers of the message:
</p>
<pre>
\N^real-([^@]+)@your\.dom\.ain$\N $1@your.dom.ain h</pre>
<p>
This means that users won't ever see the <tt>real-</tt> prefix, unless they
look at the <i>Envelope-To:</i> header.
</p>
<p>
<a name="TOC160" href="FAQ.html#TOC160">Q0414:</a> I have set <tt>caseful_local_part</tt> on the routers that handle my local
domain because my users have upper case letters in their login names,
but incoming mail now has to use the correct case. Can I relax this
somehow?
</p>
<p>
<font color="#00BB00">A0414:</font> If you really have to live with caseful user names but want incoming
local parts to be caseless, then you have to maintain a file, indexed by
the lower case forms, that gives the correct case for each login, like
this:
</p>
<pre>
admin: Admin
steven: Steven
mcdonald: McDonald
lamanch: LaManche
...</pre>
<p>
and at the start of the routers that handle your local domain, put one
like this:
</p>
<pre>
set_case_router:
driver = redirect
data = ${lookup{${lc:$local_part}}lsearch{/the/file}}
qualify_preserve_domain</pre>
<p>
For efficiency, you should also set the <tt>redirect_router</tt> option to cause
processing of the changed address to begin at the next router. If you
are otherwise using the default configuration, the setting would be
</p>
<pre>
redirect_router = system_aliases</pre>
<p>
If there are lots of users, then a DBM or cdb file would be more
efficient than a linear search. If you are handling several domains,
you will have to extend this configuration to cope appropriately.
</p>
<p>
<a name="TOC161" href="FAQ.html#TOC161">Q0415:</a> Can I use my existing alias files and forward files as well as procmail
and effectively drop in Exim in place of Sendmail ?
</p>
<p>
<font color="#00BB00">A0415:</font> Yes, as long as your alias and forward files don't assume that pipes are
going to run under a shell. If they do, you either have to change them,
or configure Exim to use a shell (which it doesn't by default).
</p>
<p>
<a name="TOC162" href="FAQ.html#TOC162">Q0416:</a> What is quickest way to set up Exim so any message sent to a
non-existing user would bounce back with a different message, based
on the name of non-existing user?
</p>
<p>
<font color="#00BB00">A0416:</font> Place this router last, so that it catches any local addresses that
are not otherwise handled:
</p>
<pre>
non_exist:
driver = accept
transport = non_exist_reply
no_verify</pre>
<p>
Then add the following transport to the transports section:
</p>
<pre>
non_exist_reply:
driver = autoreply
user = exim
to = $sender_address
subject = User does not exist
text = You sent mail to $local_part. That's not a valid user here. \
The subject was: $subject.</pre>
<p>
If you want to pick up a message from a file, you can use the <tt>file</tt>
option (use <tt>file_expand</tt> if you want its contents expanded).
</p>
<p>
<a name="TOC163" href="FAQ.html#TOC163">Q0417:</a> What do I need to do to make Exim handle <i>/usr/ucb/vacation</i> processing
automatically, so that people could just create a <i>.vacation.msg</i> file in
their home directory and not have to edit their <i>.forward</i> file?
</p>
<p>
<font color="#00BB00">A0417:</font> Add a new router like this, immediately before the normal <b>localuser</b>
router:
</p>
<pre>
vacation:
driver = accept
check_local_user
require_files = $home/.vacation.msg
transport = vacation_transport
unseen</pre>
<p>
and a matching new transport like this:
</p>
<pre>
vacation_transport:
driver = pipe
command = /usr/ucb/vacation $local_part</pre>
<p>
However, some versions of <i>/usr/ucb/vacation</i> do not work properly unless
the DBM file(s) it uses are created in advance - it won't create them
itself. You also need a way of removing them when the vacation is over.
</p>
<p>
Another possibility is to use a fixed filter file which is run whenever
<i>.vacation.msg</i> exists, for example:
</p>
<pre>
vacation:
driver = redirect
check_local_user
require_files = $home/.vacation.msg
file = /some/central/filter
allow_filter</pre>
<p>
The filter file should use the <tt>if personal</tt> check before sending mail,
to avoid generating automatic responses to mailing lists. If sending a
message is all that it does, this doesn't count as a “significant”
delivery, so the original message goes on to be delivered as normal.
</p>
<p>
Yet another possibility is to make use of Exim's <b>autoreply</b> transport,
and not use <i>/usr/ucb/vacation</i> at all.
</p>
<p>
<a name="TOC164" href="FAQ.html#TOC164">Q0418:</a> I want to use a default entry in my alias file to handle unknown local
parts, but it picks up the local parts that the aliases generate. For
example, if the alias file is
</p>
<pre>
luke.skywalker: luke
ls: luke
*: postmaster</pre>
<p>
then messages addressed to <i>luke.skywalker</i> end up at <i>postmaster</i>.
</p>
<p>
<font color="#00BB00">A0418:</font> The default mechanism works best with virtual domains, where the
generated address is not in the same domain. If you just want to pick up
all unknown local parts and send them to postmaster, an easier way to do
it is to put this as your last router:
</p>
<pre>
unknown:
driver = redirect
data = postmaster
no_verify</pre>
<p>
Another possibility is to put the redirect router for these aliases
after all the other routers, so that local parts which are user names
get picked off first. You will need to have two aliasing routers if
there are some local parts (e.g. <i>root</i>) which are login names, but which
you want to handle as aliases.
</p>
<p>
<a name="TOC165" href="FAQ.html#TOC165">Q0419:</a> I have some obsolete domains which people have been warned not to use
any more. How can I arrange to delete any mail that is sent to them?
</p>
<p>
<font color="#00BB00">A0419:</font> To reject them at SMTP time, with a customized error message, place
statments like this in the ACL:
</p>
<pre>
deny message = The domain $domain is obsolete
domains = lsearch;/etc/exim/obsolete.domains</pre>
<p>
For messages that don't arrive over SMTP, you can use a router like
this to bounce them:
</p>
<pre>
obsolete:
driver = redirect
domains = lsearch;/etc/exim/obsolete.domains
allow_fail
data = :fail: the domain $domain is obsolete</pre>
<p>
If you just want to throw away mail to those domains, accept them at
SMTP time, and use a router like this:
</p>
<pre>
obsolete:
domains = lsearch;/etc/exim/obsolete.domains
data = :blackhole:</pre>
<p>
<a name="TOC166" href="FAQ.html#TOC166">Q0420:</a> How can I arrange that mail addressed to <i>anything@something.mydomain.com</i>
gets delivered to <i>something@mydomain.com</i>?
</p>
<p>
<font color="#00BB00">A0420:</font> Set up a router like this:
</p>
<pre>
user_from_domain:
driver = redirect
data = ${if match{$domain}{\N^(.+)\.mydomain\.com$\N}\
{$1@mydomain.com}}</pre>
<p>
<a name="TOC167" href="FAQ.html#TOC167">Q0421:</a> I can't get a regular expression to work in a <tt>local_parts</tt> option on
one of my routers.
</p>
<p>
<font color="#00BB00">A0421:</font> Have you remembered to protect any backslash and dollar characters in
your regex from unwanted expansion? The easiest way is to use the
<tt>\N</tt> facility, like this:
</p>
<pre>
local_parts = \N^0740\d{6}\N</pre>
<p>
<a name="TOC168" href="FAQ.html#TOC168">Q0422:</a> How can I arrange for all addresses in a group of domains <i>*.example.com</i>
to share the same alias file? I have a number of such groups.
</p>
<p>
<font color="#00BB00">A0422:</font> For a single group you could just hard wire the file name into a router
that had
</p>
<pre>
domains = *.example.com</pre>
<p>
set, to restrict it to the relevant domains. For a number of such groups
you can create a file containing the domains, like this:
</p>
<pre>
*.example1.com example1.com
*.example2.com example2.com
...</pre>
<p>
Then create a router like this
</p>
<pre>
domain_aliases:
driver = redirect
domains = partial-lsearch;/that/file
data = ${lookup{$local_part}lsearch*{/etc/aliases.d/$domain_data}}</pre>
<p>
The variable <i>$domain_data</i> contains the data that was looked up when the
<tt>domains</tt> option was matched, i.e. <tt>example1.com</tt>, <tt>example2.com</tt>, etc.
in this case.
</p>
<p>
<a name="TOC169" href="FAQ.html#TOC169">Q0423:</a> Some of our users have no home directories; the field in the password
file contains <i>/no/home/dir</i>. This causes the error <i>failed to stat
/no/home/dir (No such file or directory)</i> when Exim tries to look for a
<i>.forward file</i>, and the delivery is deferred.
</p>
<p>
<font color="#00BB00">A0423:</font> There are two issues involved here:
</p>
<p>
(1) With the default configuration, you are asking Exim to check for a
<i>.forward</i> file in the user's home directory. If no file is found,
Exim tries to <i>stat()</i> the home directory. This is so that it will
notice a missing NFS home directory, and not treat it as if the
<i>.forward</i> file did not exist. This <i>stat()</i> is failing when the
home directory really doesn't exist. You should arrange for the
<b>userforward</b> router not to run for these special users, by adding
this line:
</p>
<pre>
condition = ${if eq {$home}{/no/home/dir}{no}{yes}}</pre>
<p>
(2) If you use <tt>check_local_user</tt> on another router to route to a local
transport (again, this is what is in the default configuration), you
will also have to specify a current directory for the transport, because
by default it makes the home directory current. This is easily done by
adding
</p>
<pre>
current_directory = /</pre>
<p>
to the transport or
</p>
<pre>
transport_current_directory = /</pre>
<p>
to the router. Or you can add <tt>home_directory</tt> to the transport, because
the current directory defaults to the home directory.
</p>
<p>
<a name="TOC170" href="FAQ.html#TOC170">Q0424:</a> How can I disable Exim's de-duplication features? I want it to do two
deliveries if two different aliases expand to the same address.
</p>
<p>
<font color="#00BB00">A0424:</font> This is not possible. Duplication has other ramifications other than
just (in)convenience. Consider:
</p>
<p>
. Message is addressed to A and to B.
</p>
<p>
. Both A and B are aliased to C.
</p>
<p>
. Without de-duplication, two deliveries to C are scheduled.
</p>
<p>
. One delivery happens, Exim records that it has delivered the message
to C.
</p>
<p>
. The next delivery fails (C's mailbox is over quota, say).
</p>
<p>
Next time round, Exim wants to know if it has already delivered to C or
not, before scheduling a new delivery. Has it? Obviously, if duplicate
deliveries are supported, it has to remember not only that it has
delivered to C but also the “history” of how that delivery happened - in
effect an ancestry list back to the original envelope address. This it
does not do, and changing it to work in that way would be a lot of work
and a big upheaval.
</p>
<p>
The best way to get duplicate deliveries if you want them is not to use
aliases, but to route the addresses directly to a transport, e.g.
</p>
<pre>
duplicates:
driver = accept
local_parts = lsearch;/etc/list/of/special/local/parts
transport = local_delivery
user = exim</pre>
<p>
<a name="TOC171" href="FAQ.html#TOC171">Q0425:</a> My users' mailboxes are distributed between several servers according to
the first letter of the user name. All the servers receive incoming mail
at random. I would like to have the same configuration file for all the
servers, which does local delivery for the mailboxes it holds, and sends
other addresses to the correct other server. Is this possible?
</p>
<p>
<font color="#00BB00">A0425:</font> It is easiest if you arrange for all the users to have password entries
on all the servers. This means that non-existent users can be detected
at the first server they reach. Set up a file containing a mapping from
the first letter of the user names to the servers where their mailboxes
are held. For example:
</p>
<pre>
a: server1
b: server1
c: server2
...</pre>
<p>
Before the normal <b>localuser</b> router, place the following router:
</p>
<pre>
mailbox_host:
driver = manualroute
check_local_user
transport = remote_smtp
route_list = * ${lookup{${substr_0_1:$local_part}}lsearch{/etc/mapfile}}
self = pass</pre>
<p>
This router checks for a local account, then looks up the host from the
first character of the local part. If the host is not the local host,
the address is routed to the <b>remote_smtp</b> transport, and sent to the
correct host. If the host is the local host, the <tt>self</tt> option causes
the router to pass the address to the next router, which does a local
delivery.
</p>
<p>
The router is skipped for local parts that are not the names of local
users, and so these addresses fail.
</p>
<p>
<a name="TOC172" href="FAQ.html#TOC172">Q0426:</a> One of the things I want to set up is for <i>anything@onedomain</i> to forward
to <i>anything@anotherdomain</i>. I tried adding <i>$local_part@anotherdomain</i> to
my aliases but it did not expand - it sent it to that literal address.
</p>
<p>
<font color="#00BB00">A0426:</font> If you want to do it that way, you can use the <tt>expand</tt> operator on
the lookup used in the data option of the redirect router. For example:
</p>
<pre>
data = ${expand:${lookup{$local_part}lsearch*{/etc/aliases}}}</pre>
<p>
Another approach is to use a router like this:
</p>
<pre>
forwarddomain:
driver = redirect
domains = onedomain
data = $local_part@anotherdomain</pre>
<p>
The value of <tt>data</tt> can, of course, be more complicated, involving
lookups etc. if you have lots of different cases.
</p>
<p>
<a name="TOC173" href="FAQ.html#TOC173">Q0427:</a> How can I have an address looked up in two different alias files, and
delivered to all the addresses that are found?
</p>
<p>
<font color="#00BB00">A0427:</font> Use a router like this:
</p>
<pre>
multi_aliases:
driver = redirect
data = ${lookup{$local_part}lsearch{/etc/aliases1}\
{$value${lookup{$local_part}lsearch{/etc/aliases2}{,$value}}}\
{${lookup{$local_part}lsearch{/etc/aliases2}{$value}fail}}}\</pre>
<p>
If the first lookup succeeds, the result is its data, followed by the
data from the second lookup, if any, separated by a comma. If the first
lookup fails, the result is the data from the third lookup (which also
looks in the second file), but if this also fails, the entire expansion
is forced to fail, thereby causing the router to decline.
</p>
<p>
Another approach is to use two routers, with the first re-generating the
original local part when it succeeds. This won't get processed by the
same router again. For example:
</p>
<pre>
multi_aliases1:
driver = redirect
data = ${lookup{$local_part}lsearch{/etc/aliases1}{$value,$local_part}}</pre>
<pre>
multi_aliases2:
data = ${lookup{$local_part}lsearch{/etc/aliases2}}</pre>
<p>
This scales more easily to three or more alias files.
</p>
<p>
<a name="TOC174" href="FAQ.html#TOC174">Q0428:</a> I've converted from Sendmail, and I notice that Exim doesn't make use
of the <tt>owner-</tt> entries in my alias file to change the sender address in
outgoing messages to a mailing list.
</p>
<p>
<font color="#00BB00">A0428:</font> If you have an alias file with entries like this:
</p>
<pre>
somelist: a@b, c@d, ...
owner-somelist: postmaster</pre>
<p>
Sendmail assumes that the second entry specifies a new sender address
for the first. Exim does not make this assumption. However, you can make
it take the same action, by adding
</p>
<pre>
errors_to = owner-$local_part@whatever.domain</pre>
<p>
to the configuration for your aliasing router. This is fail-safe,
because Exim verifies a new sender address before using it. Thus, the
change of sender address occurs only when the owner entry exists.
</p>
<p>
<a name="TOC175" href="FAQ.html#TOC175">Q0429:</a> I would like to deliver mail addressed to a given domain to local
mailboxes, but also to generate messages to the envelope senders.
</p>
<p>
<font color="#00BB00">A0429:</font> You can do this with an “unseen” router and an <b>autoreply</b> transport,
along the following lines:
</p>
<pre>
# Router
auto_warning_r:
driver = accept
check_local_user
domains = <domains you want to do this for>
condition = ${if eq{$sender_address}{}{no}{yes}}
transport = warning_t
no_verify
unseen</pre>
<p>
Place this router immediately before the normal <b>localuser</b> router. The
<tt>unseen</tt> option means that the address is still passed on to the next
router. The transport is configured like this:
</p>
<pre>
# Transport
warning_t:
driver = autoreply
file = /usr/local/mail/warning.txt
file_expand
from = postmaster@your.domain
to = $sender_address
user = exim
subject = Re: Your mail to $local_part@$domain</pre>
<p>
Note the use of the <tt>condition</tt> option to avoid attempting to send a
message when there is no sender (that is, when the incoming message is a
bounce message). You can of course extend this to include other
conditions. If you want to log the sending of messages, you can add
</p>
<pre>
log = /some/file</pre>
<p>
to the transport and also make use of the <tt>once</tt> option if you want to
send only one message to each sender.
</p>
<p>
<a name="TOC176" href="FAQ.html#TOC176">Q0430:</a> Whenever Exim tries to route a local address, it gives a permission
denied error for the <i>.forward</i> file, like this:
</p>
<pre>
1998-08-10 16:55:32 0z5y2W-0000B8-00 == xxxx@yyy.zzz <xxxx@yyy.zz>
D=userforward defer (-1): failed to open /home/xxxx/.forward
(userforward router): Permission denied (euid=1234 egid=101)</pre>
<p>
<font color="#00BB00">A0430:</font> Have you remembered to make Exim setuid <i>root</i>?
</p>
<p>
<a name="TOC177" href="FAQ.html#TOC177">Q0431:</a> How do I configure Exim to allow arbitrary extensions in local parts, of
the form <i>+extension</i>?
</p>
<p>
<font color="#00BB00">A0431:</font> Add this pre-condition to the relevant router:
</p>
<pre>
local_part_suffix = +*</pre>
<p>
If you want the extensions to be optional, also add the option
</p>
<pre>
local_part_suffix_optional</pre>
<p>
When the router runs, <i>$local_part</i> contains the local part with the
extension removed, and the extension (if any) is in <i>$local_part_suffix</i>.
If you have set <tt>check_local_user</tt>, the test is carried out after the
extension is removed.
</p>
<p>
<a name="TOC178" href="FAQ.html#TOC178">Q0432:</a> I use NIS for my user data. How can I stop Exim rejecting mail when my
NIS servers are being restarted?
</p>
<p>
<font color="#00BB00">A0432:</font> Exim doesn't know that you are using NIS; it just calls the <i>getpwnam()</i>
function, which is routed by nsswitch. Unfortunately, <i>getpwnam()</i>
was never designed to be routed through NIS, and it returns NULL if the
entry is not found or if the connection to the NIS server fails. This
means that Exim cannot tell the difference between “no such user” and
“NIS is down”.
</p>
<p>
Crutches to help with this problem are <tt>finduser_retries</tt> in Exim, and
<i>nscd</i> on the Unix side, but they are not perfect, and mail can still
be lost. However, Nico Erfurth pointed out that you can create a router
for Exim that tests for the availability of NIS, and force a defer if
NIS is not running:
</p>
<pre>
check_nis:
driver = redirect
data = ${lookup {$local_part} nis {passwd}{}}</pre>
<p>
This should be placed before any router that makes any use of NIS,
typically at the start of your local routers. How does it work? If
your NIS server is reachable, the lookup will take place, and whether it
succeeds or fails, the result is an empty string. This causes the
router to decline, and the address is passed to the following routers.
If your NIS server is down, the lookup defers, and this causes the
router to defer. A verification of an incoming address gets a temporary
rejection, and a delivery is deferred till later.
</p>
<p>
<a name="TOC179" href="FAQ.html#TOC179">Q0433:</a> How can I arrange for a single address to be processed by both
<b>redirect</b> and <b>accept</b>?
</p>
<p>
<font color="#00BB00">A0433:</font> Check out the <tt>unseen</tt> option.
</p>
<p>
<a name="TOC180" href="FAQ.html#TOC180">Q0434:</a> How can I redirect all local parts that are not in my system aliases to
a single address? I tried using an asterisk in the system alias file
with an <tt>lsearch*</tt> lookup, but that sent all messages to the
default address.
</p>
<p>
<font color="#00BB00">A0434:</font> If your alias file generates addresses in the local domain, they are
also processed as a potential aliases. For example, suppose this is your
alias file:
</p>
<pre>
caesar: jc
anthony: ma
*: brutus</pre>
<p>
The local part <i>caesar</i> is aliased to <i>jc</i>, but that address is then
reprocessed by the routers. As the address is in the local domain, the
alias file is again consulted, and this time the default matches. In
fact after the second aliasing, <i>brutus</i> is also processed again from
the start, and is aliased to itself. However, this happens only once,
because the next time, Exim notices that the aliasing router has already
processed <i>brutus</i>, so the router is skipped in order to avoid
looping.
</p>
<p>
There are several ways of solving this problem; which one you use
depends on your aliasing data.
</p>
<p>
(1) If the result of aliasing is always a local user name, that is,
aliasing never generates another alias, you can use the
<tt>redirect_router</tt> option on the router to specify that processing
the generated addresses must start at the next router. For example:
</p>
<pre>
redirect_router = userforward</pre>
<p>
assuming that the next router is called <b>userforward</b>. This
ensures that there is at most one pass through the aliasing router.
</p>
<p>
(2) If you cannot rely on aliases generating non-aliases, it is often
easier not to use a default alias, but instead to place a router
such as the one below after all the other local routers (for the
relevant domains):
</p>
<pre>
catch_unknown:
driver = redirect
domains = ...
data = brutus@$domain</pre>
<p>
Note that the default aliasing technique works more successfully for
virtual domains (see <a href="FAQ_4.html#TOC147">Q0401</a>) because the generated address for the
default is not usually in the same virtual domain as the incoming
address.
</p>
<p>
<a name="TOC181" href="FAQ.html#TOC181">Q0435:</a> My alias file contains fully qualified addresses as keys, and some
wildcard domains in the form @foo.bar. Can Exim handle these?
</p>
<p>
<font color="#00BB00">A0435:</font> You can handle fully qualified addresses with this router:
</p>
<pre>
qualified_aliases:
driver = redirect
data = ${lookup{$local_part@$domain}lsearch{/etc/aliases}}</pre>
<p>
(Add any other options you need for the <b>redirect</b> router.) Place this
router either before or after the default aliases router that looks up
the local part only. (Or, if you have no unqualified aliases, replace
the default router.)
</p>
<p>
To handle wildcards in the form @foo.bar you will need yet another
router. (Wildcards of the form *@foo.bar can be handled by an lsearch*@
lookup.) Something like this:
</p>
<pre>
wildcard_aliases:
driver = redirect
data = ${lookup{@$domain}lsearch{/etc/aliases}}</pre>
<p>
Place this after the routers that handle the more specific aliases.
</p>
<hr><br>
<a href="FAQ.html#TOC">Contents</a>
<a href="FAQ_3.html">Previous</a>
<a href="FAQ_5.html">Next</a>
</body>
</html>
