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<HTML>
<HEAD>
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<TITLE>Exim Specification - 21. Additional generic options for directors</TITLE>
</HEAD>
<body bgcolor="#FFFFFF" text="#00005A" link="#FF6600" alink="#FF9933" vlink="#990000">
Go to the <A HREF="spec_1.html">first</A>, <A HREF="spec_20.html">previous</A>, <A HREF="spec_22.html">next</A>, <A HREF="spec_59.html">last</A> section, <A HREF="spec_toc.html">table of contents</A>.
<P><HR><P>
<H1><A NAME="SEC601" HREF="spec_toc.html#TOC601">21. Additional generic options for directors</A></H1>
<P>
<A NAME="IDX1411"></A>
<A NAME="IDX1412"></A>
</P>
<P>
The following additional generic options apply to all directors, in addition to
the generic options common to both directors and routers which are described in
chapter 20. Directors are concerned with addresses whose
domains match something in <EM>local_domains</EM>, or which have been explicitly
determined to be local by a router.
</P>
<P>
<P>
<A NAME="IDX1413"></A>
<H3><A NAME="SEC602" HREF="spec_toc.html#TOC602">current_directory (director)</A></H3>
<P>
Type: string, expanded<BR>
Default: unset
</P>
<P>
This option associates a current directory with any address that a director
directs to a local transport. This can happen either because a transport is
explicitly configured for the director, or because it generates a delivery to a
file or a pipe. During the delivery process (that is, at transport time), this
option string is expanded and is set as the current directory, unless
overridden by a setting on the transport. See chapter 13 for
details of the local delivery environment. The <EM>forwardfile</EM> director handles
this option in a special way (see section 24.6).
</P>
<P>
<A NAME="IDX1414"></A>
<H3><A NAME="SEC603" HREF="spec_toc.html#TOC603">expn (director)</A></H3>
<P>
Type: boolean<BR>
Default: true
</P>
<P>
<A NAME="IDX1415"></A>
<A NAME="IDX1416"></A>
If this option is turned off, the director is skipped when testing an address
as a result of processing an SMTP EXPN command. You might, for example,
want to turn it off on a director for users' <TT>`.forward'</TT> files, while leaving it
on for the system alias file. The use of the SMTP EXPN command is permitted
only from hosts that match the <EM>smtp_expn_hosts</EM> main configuration option.
</P>
<P>
This option is specific to directors because EXPN applies only to local
addresses, so no address that is an argument to EXPN is ever passed to any
router. When Exim is running an EXPN command, it is similar to testing
an address with -<EM>bt</EM>. Compare VRFY, whose counterpart is -<EM>bv</EM>.
</P>
<P>
<A NAME="IDX1417"></A>
<H3><A NAME="SEC604" HREF="spec_toc.html#TOC604">home_directory (director)</A></H3>
<P>
Type: string, expanded<BR>
Default: unset
</P>
<P>
This option associates a home directory with any address that a director
directs to a local transport. This can happen either because a transport is
explicitly configured for the director, or because it generates a delivery to a
file or a pipe. During the delivery process (that is, at transport time), the
option string is expanded and is set as the home directory, unless overridden
by a setting on the transport. This means that the expansion variable $<EM>home</EM>
does not take on this value at directing time. In particular, it cannot be used
in the <EM>require_files</EM> option. See chapter 13 for details of
the local delivery environment. The <EM>forwardfile</EM> and <EM>localuser</EM> directors
handle this option in a special way (see section 24.6).
</P>
<P>
<A NAME="IDX1418"></A>
<H3><A NAME="SEC605" HREF="spec_toc.html#TOC605">new_director (director)</A></H3>
<P>
Type: string<BR>
Default: unset
</P>
<P>
Sometimes an administrator knows that it is pointless to reprocess addresses
generated from alias or forward files with the same director again. For
example, if an alias file translates real names into login ids there is no
point searching the alias file again, especially if it is a large file.
</P>
<P>
The <EM>new_director</EM> option can be set to the name of any director instance. It
causes the directing of any generated local addresses to start at the named
director instead of the first director. The named director can be any
configured director. This option has no effect if the director in which it is
set does not generate new addresses, or if such addresses are not in local
domains.
</P>
<P>
<A NAME="IDX1419"></A>
<H3><A NAME="SEC606" HREF="spec_toc.html#TOC606">prefix (director)</A></H3>
<P>
Type: string list<BR>
Default: unset
</P>
<P>
If this option is set, the director is skipped unless the local part
starts with one of the given strings, or the <EM>prefix_optional</EM> option is true.
<font color=green>
The list is scanned from left to right, and the first prefix that matches is
used.
</font>
A limited form of wildcard is available; if the prefix begins with an asterisk,
it matches the longest possible sequence of arbitrary characters at the start
of the local part. An asterisk should therefore always be followed by some
character that does not occur in normal local parts.
<A NAME="IDX1420"></A>
<A NAME="IDX1421"></A>
Wildcarding can be used to
set up multiple user mailboxes, as described in chapter 41.
</P>
<P>
While the director is running, the prefix is removed from the local part, and is
available in the expansion variable <EM>local_part_prefix</EM>. If the director
succeeds, this remains true during subsequent delivery.
</P>
<P>
The prefix facility is commonly used to handle local parts of the form
<EM>owner-something</EM>. Another common use is to support local parts of the form
<EM>real-username</EM> to bypass a user's <TT>`.forward'</TT> file -- helpful when trying to
tell a user their forwarding is broken -- by placing a director like this one
immediately before the director that handles <TT>`.forward'</TT> files:
<PRE>
real_localuser:
driver = localuser
transport = local_delivery
prefix = real-
</PRE>
<P>
If both <EM>prefix</EM> and <EM>suffix</EM> are set for a director, both conditions must be
met if not optional. Care must be taken if wildcards are used in both a prefix
and a suffix on the same director. Different separator characters must be used
to avoid ambiguity.
</P>
<P>
<A NAME="IDX1422"></A>
<H3><A NAME="SEC607" HREF="spec_toc.html#TOC607">prefix_optional (director)</A></H3>
<P>
Type: boolean<BR>
Default: false
</P>
<P>
See <EM>prefix</EM> above.
</P>
<P>
<A NAME="IDX1423"></A>
<H3><A NAME="SEC608" HREF="spec_toc.html#TOC608">suffix (director)</A></H3>
<P>
Type: string list<BR>
Default: unset
</P>
<P>
This option operates in the same way as <EM>prefix</EM>, except that the local part
must end (rather than start) with the given string, the <EM>suffix_optional</EM>
option determines whether the suffix is mandatory, and the wildcard *
character, if present, must be the last character of the suffix. This option
facility is commonly used to handle local parts of the form
<EM>something-request</EM> and multiple user mailboxes of the form <EM>username-foo</EM>.
</P>
<P>
<A NAME="IDX1424"></A>
<H3><A NAME="SEC609" HREF="spec_toc.html#TOC609">suffix_optional (director)</A></H3>
<P>
Type: boolean<BR>
Default: false
</P>
<P>
See <EM>suffix</EM> above.
</P>
<H2><A NAME="SEC610" HREF="spec_toc.html#TOC610">21.1 Skipping directors</A></H2>
<P>
<A NAME="IDX1425"></A>
<A NAME="IDX1426"></A>
Section 20.1 above describes the circumstances in which the generic
options that are common to both directors and routers cause a driver to be
skipped. Directors have additional generic options which impose some further
condition.
</P>
<P>
The <EM>new_director</EM> generic option causes the directing of a generated local
address to start at a particular director, thus skipping those above it for
that address.
</P>
<P>
Processing of the <EM>prefix</EM> and <EM>suffix</EM> options does not happen until after the
check of <EM>local_parts</EM> is done,
so the local part that is checked at that stage is the full local part. If you
want to select a director based on a partial local part, you can use a regular
expression, or make use of the <EM>condition</EM> option to do more complicated
processing (such as looking up a prefix-stripped local part in a file).
</P>
<P>
The following additional conditions, which are applied after the initial checks
on the domain etc., prevent the current director from being run:
</P>
<UL>
<LI>
An SMTP EXPN command is being processed and the director's <EM>expn</EM> option is
turned off, or
<LI>
There is a prefix or suffix mismatch, or
<LI>
The address was generated by aliasing or forwarding and is identical to an
ancestor address that was processed by this director. This restriction breaks
addressing loops.
</UL>
<P><HR><P>
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