13.1 Internal Mailing Lists
An internal
mailing list is simply an entry in the aliases
file that has more than one recipient listed on the right-hand side.
Consider, for example, the following aliases
file entries:
admin: bob,jim,phil
bob: \bob,/u/bob/admin/maillog
Here, the name admin is actually the name of a
mailing list because it expands to more than one recipient.
Similarly, the name bob is a mailing list because
it expands to two recipients. Because bob is also
included in the admin list, mail sent to that
mailing list will be alias-expanded by sendmail
to produce the following list of recipients:
jim, phil, \bob, /u/bob/admin/maillog
This causes the mail message to be delivered to the local users
jim and phil in the normal way.
That is, each undergoes additional alias processing, and the
~/.forward file of each is examined to see
whether either should be forwarded. The recipient
\bob, on the other hand, is delivered without any
further aliasing because of the leading backslash. Finally, the
message is appended to the file
/u/bob/admin/maillog.
Internal mailing lists can become very complex as they strive to
support the needs of large institutions. Examine the following
simple, but revealing, example:
research: user1, user2
applications: user3, user4
admin: user5, user6
advertising: user7, user8
engineering: research, applications
frontoffice: admin, advertising
everyone: engineering, frontoffice
Only the first four aliases expand to real usernames. The last three
form mailing lists out of combinations of those four, the last being
a superset that includes all users.
When the number of mailing lists is small and they
don't change often, they can be effectively managed
as part of the aliases file. But as their number
and size grow, you should consider moving individual lists to
external files.
|