Re: [Exim] backup MX setup...

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Author: Philip Hazel
Date:  
To: Matthew Dunham
CC: exim-users
Subject: Re: [Exim] backup MX setup...
On Fri, 18 Aug 2000, Matthew Dunham wrote:

> i plan to have 3 mx records for my domain with preferences of, say, 0,
> 10, and 20. the highest preference mx (0) will be the main server with
> the other two as backup mx's.


Do not use 0. Use 10, 20, 30. That gives you room to insert anywhere.

> in the case of a main server outage, the next highest preference (10)
> will spool mail for the main server as long as i've set my domain in
> relay_domains. correct?


on the (10) server, yes.

> and then if both (0) and (10) are out, the
> preference (20) server will spool the messages. so when the
> lower-preferenced systems come back up, the preference (20) server will
> dump its spooled messages based on the local_domains setting? and it
> does this based on the retry configuration?


Nothing to do with local_domains. The setting of local_domains on the
(20) server is for *its* domains, not yours. It will send out the
spooled mail as soon as either of the other servers will accept it, but
it will use the retry rules to decide when to try them.

> and what transports/directors/routers need to be set up to mediate this
> dumping of spooled messages to the lower-preferenced servers? or is this
> handled automagically by the relay_domains setting?


Assuming you have an otherwise standard configuration, all you need to
set is relay_domains. That allows the server to accept the mail for
relaying. The actual delivery is not special and is handled the same way
as any other delivery (e.g. if somebody actually on the (20) server sends
a message to your domain).


-- 
Philip Hazel            University of Cambridge Computing Service,
ph10@???      Cambridge, England. Phone: +44 1223 334714.