Re: [EXIM] Basic mail handling question

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Auteur: Peter Radcliffe
Date:  
À: exim-users
Sujet: Re: [EXIM] Basic mail handling question
Randy Edwards <redwards@???> probably said:
> a Linux server with Exim. Each site has a different set of users
> but all sites operate under one domain. Each site's users changes a


Theres your problem. "one domain".
If you want all users at three sites to be in one domain you're pretty
much stuck with maintaining a list and having a copy at all three sites.

One alternative is having an "unknown" director that takes unknown local
mail and forwards it onto the next machine, but worst case mail could
have to travel through all three servers to get to the right place,
not a Good Thing especially with slow links and if one of the sites
goes down it would prevent mail for other sites being delivered.

> Can someone explain to me how I'd go about linking all of these
> sites up for mail. For example, if I have the domain's incoming
> mail server at Site 1, how can I automagically send mail for users
> at site 3 down to site 3's server? Would I have to have all users
> entered on site 1's server (hardly seems practical)? Is there a way


Either you drop the one domain stuff and have site1.dom.ain,
site2.dom.ain, site3.dom.ain and point MX records appropriately or
you are going to have mail going to the wrong site sometimes because
there is no way to break a single MX record down to multiple sites.

If I had to do this with several sites I'd have an aliasfile covering
@dom.ain, including all users from all three sites, a copy at all
three sites. Handle this like a virtual domain (there are some nice
virtual domain example configs in the examples).
The aliases point to foo@???. Have MX records for dom.ain
pointing to site1, site2 and site3. You may want to weight them by
number of users (so its most likely mail ends up at the site that has
the most people).

If it arrives at the wrong site, or someone sends mail to someone who
is at a different site it gets sorted by the aliasfile and delivered
to the right place. You'd have to centrally manage adding people to the
aliasfile and dist it out somehow.
qualify_domain should be dom.ain. THe primary domain of each should be
siteN.dom.ain.

It would be nicer if you had somewhere on a fast net link to do the
sorting before it goes down the slow links (co-located box or something)
and then you do exactly the same thing, but have the primary MX point
at the sorting machine (if it goes down then you just use the 2ndary MXs,
the sites themselves). An ISP that does virtual domains could do this
for you on their mail relays, probably.

P.

-- 
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