[PLUG] MX seconding and fetchmail

[Ian Burrell]

Jeme A Brelin wrote:
> 
> I may be moving my home network in a little while.  No assurance that
>  I can get any kind of overlap on the network connectivity, so I'm 
> considering a kind of stop-gap measure that could possibly be a 
> permanent fail-over solution for my mail.
> 
> There are some assumptions here about the way things work that I've 
> never used before, so please pipe up if I write something nutso.
> 
> I figure I'll set my domains' secondary MX to some machine off-net 
> (that is to say, not at the end of my DSL connection).  That machine 
> will be configured to deliver ALL mail for my domains to a single 
> mailbox accessible by some remote retrieval protocol.  Then, whenever
>  my primary MX is unavailable, the mail will be delivered to the 
> secondary. Periodically, my primary MX will launch a fetchmail 
> process to grab all the mail from the secondary MX and deliver it 
> locally according to the local MTA's configuration.
> 

I don't think mail servers can be configured to try the primary and
deliver locally if it can't be reached.  They either are a secondary,
queueing mail for the primary MX.  Or they deliver the mail locally.

If your local server is going to be down for a while, I would setup the 
remote site to accept the mail and use fetchmail to retrieve it.  If the 
downtime is going to be short, then setup the secondary and let it queue 
the mail.

> Does that all sound quite sane and reasonable?  The initial delivery 
> to the secondary MX shouldn't mess with any of the envelope 
> information of the messages and prevent them from being delivered to 
> disparate mailboxes on the primary, will it?
> 

With many mail servers, the SMTP recipient is completely lost
once the message is delivered.  This can create problems when splitting 
to multiple mailboxes.  This happens especially with mailing lists and 
similar where the receipient is not found in the headers.  Postfix and 
qmail add the Delivered-To header with the receipient.  This can be used 
by fetchmail.

> This seems so straightforward, I would think it's probably common 
> practice in some circles (unless there's a configuration within the
> MTA to do the failover and re-delivery).
> 

Fetchmail works with the fetching remove mailbox and delivering it 
locally with multiple mailboxes.

  - Ian

-- 
ian at znark.com
http://www.znark.com/