[wplug] Mailman and Postfix

Jonathan S. Billings wbanguna at gmail.com
Thu Jan 24 09:55:45 EST 2008


On Thu, Jan 24, 2008 at 09:33:20AM -0500, Christopher DeMarco wrote:
> On Thu, Jan 24, 2008 at 06:34:54AM -0500, Jonathan S. Billings wrote:
> 
> > > When do we change the DNS records and how do we coordinate that with
> > > moving the lists?
> > 
> > I see you don't have an MX record for wplug.org.  I suggest creating
> > one NOW, referring to penguin.wplug.org and with a low TTL, like 5
> > minutes, so you can switch it over quickly when you do want to make
> > the move.  That way, when you want to move the lists over to linode,
> > it's as simple as updating the MX record with the new A record.
> 
> Better yet:
> 
> Create *two* MX records; a low value for the current one and a high
> for the new one.  Once you're ready to go with the new host,
> disable/firewall/whatever the old host, and mail will automagically
> flow to the new one.  If you wanna failback to the old host, simply
> turn it back on and voila!  

I wouldn't suggest having an MX record refer to linode until you're
sure it'll be doing the right thing with the email.  Otherwise, you're
going to drop mail, users will get strange bounces or errors, or
messages won't arrive at the right list.  I know that a
well-thought-out MTA should choose the low MX first, but the world
runs on poorly-thought-out software.  

Maybe once everything is up and running on linode, penguin can be a
backup MX that stores-and-forwards, but there are good reasons to
avoid that.

(My philosophy is that for a domain, all MXs should be virtually
identical, with shared or connected backends for any service they run
beyond mail queuing.  I assume that mailman isn't going to be set up
to sync between the two MXs.)

-- 
Jonathan Billings <wbanguna at gmail.com>


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