[exim] switching mail servers

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Lähettäjä: Jonathan Addleman
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Vastaanottaja: exim-users
Aihe: [exim] switching mail servers
Can anyone suggest some documentation relating to moving a running exim
installation to a new server? I have a system already in place on one
machine, but I'm in the process of moving everything over to another
one. Currently, mail is received locally for a number of users who
generally access it via imap. (mail stored in ~/Maildir).

I will have to switch the DNS over and copy existing mailboxes, of
course, but I want to make sure no messages are lost. I figured the
safest approach would probably be something like this:

- First set a very low DNS TTL.

- Get exim to stop delivering local messages. (either keep them in the
queue, or deliver them to a temporary file)

- Sync all the mailboxes on the old server to the new one.

- Switch the DNS over.

- Once the old server stops receiving messages, resend the temporarily
held ones.


Maybe there are better approaches though? I'm not sure the best way to
go about step 2 either - maybe using the 'queue_only' config, and then,
after everything is switched over, configure exim to relay mail to the
domain, and process the queue normally? Or somehow manually transfer the
queued messages to the new server via scp and then process them there?

Another possibility I considered is to set something up so a temporary
error is returned from the old server, so that messages will just get
resent by the originating servers later.

It's a very low-volume server, with only a few accounts, but I'd like to
do this The Right Way to avoid any bounces. Any suggestions are welcome!

--
Jon-o Addleman - http://www.redowl.ca