README.EXIM

In order for Majordomo 2 and Exim to work together, Exim
must be able to read the majordomo aliases.  This is
easy to do if the file and directory permissions are set
appropriately.

When Exim is compiled, a default user and group are established.
These values can be changed using Exim's "exim_user"
and "exim_group" configuration options.  When Exim reads 
majordomo's alias file, it does so as this user and group.
Because these values may be different from Majordomo's
user and group,  the alias files and ALIASES directory
are created with slightly relaxed permissions.

When you install Majordomo, you will be advised to 
add a Director to your Exim configuration file.
That Director will look something like this:

majordomo_aliases:
    driver = aliasfile
    pipe_transport = address_pipe
    suffix = "+*"
    suffix_optional
    user = majordom
    domains = lsearch;/usr/local/majordomo/ALIASES/mj-domains
    file = /usr/local/majordomo/ALIASES/mj-alias-$domain
    search_type = lsearch

The suffix and suffix_optional settings instruct Exim to 
treat a "+" and any succeeding characters in an address as
a suffix.  This is important because Majordomo will deliver list
messages with a suffix indicating the sequence number of the
message.  For example, the ninth message sent to the list
  tangerine@example.com
will likely cause some delivery error notices to be sent to the address
  tangerine-owner+M9@example.com
The suffix settings tell Exim to remove the "+M9" when it
attempts to determine how to deliver the error notice.

More information on configuring Exim Directors may be found 
in the specification "spec.txt" in the Exim distribution, or at
  http://www.exim.org/docs.html
 
If Majordomo is configured to use queueing, if the queue file
cannot be written due to a disk space shortage or other mishap,
the mj_enqueue program may return 73 or 74 (EX_CANTCREAT or EX_IOERR).
If you wish to treat such errors as temporary, and have Exim
try to deliver the message again later, use the Exim setting:
  temp_errors = 73:74:75
On most systems, these values will correspond to EX_CANTCREAT,
EX_IOERR, and EX_TEMPFAIL, respectively.