Postfix (mail server) question

[Robert Brockway]

On Fri, 11 Jul 2008, Jamon Camisso wrote:

I wrote:

>> luser_relay is nice because it is low maintenance.  If the user doesn't 
>> exist locally send it off to another box to deal with.
>
> If the user exists with the same name on both machines it won't be forwarded.

Remember that the usernames don't matter.  What matters is whether there 
is somewhere to deliver the mail to.  Email addresses and usernames can 
have a many to many mapping.

luser_relay is typically used in the situation where where several MTAs 
collectively handle the mail for a given organisation.  In all situations 
where I've used it, or seen it used, email and user accounts are centrally 
managed.  Using luser_relay without central management would be tricky.

It is often used where a company has many branch offices.  Rather than 
have mail for your local co-workers relay into a central core and back out 
to the same office (a waste of time and bandwidth) a check is carried out 
to see if the user exists locally before passing the mail on to the 
central post office for delivery elsewhere in the organisation.

> Don't forget about just plain /etc/aliases or procmail too ;)

Well first off let me say I love procmail :)  I typically use it as an 
LDA.  A warning to anyone wanting to try out procmail: keep backups.

Procmail is not tolerant of mistakes.  Read man procmailrc and procmailex 
for some good advice on backing up mail while playing with your procmail 
rules.

As for aliases, in general I prefer to use a virtual map (Postfix) or 
virtusertable (Sendmail) for these sorts of things.  This approach partly 
came out of having to wrestle with non-obvious interactions of the various 
maps in Sendmail many years ago.  Settling on one map for most of the work 
made things conceptually simpler and the virtual map has a lot more 
flexibility.

Aliases have some really useful capabilites of course like being able to 
pipe the mail to a process for further processing.

Cheers,

Rob

-- 
"With sufficient thrust, pigs fly just fine..."
 	-- RFC 1925 "The Twelve Networking Truths"
--
The Toronto Linux Users Group.      Meetings: http://gtalug.org/
TLUG requests: Linux topics, No HTML, wrap text below 80 columns
How to UNSUBSCRIBE: http://gtalug.org/wiki/Mailing_lists