[BlueOnyx:01610] Re: Secondary Mail Server

[Rickard Osser]

On Wed, 2009-07-08 at 12:24 +0100, Darren Wolfe wrote:
> 
> >  
> > > > >
> > > > > In the update on the 22/03/09, support was added for “secondary
> > mail
> > > > > server”.
> > > > >
> > > > >
> > > > >
> > > > > I assume this is used as a backup mail server that holds all the
> > > > > e-mail in a queue and passes it to the primary once it comes back
> > > > > online.
> > > > >
> > > > >
> > > > >
> > > > > How is it configured, and what do I need to know about it in
> > > > > operation ?
> > > >
> > > > Hi Darren,
> > > >
> > > > just add the domains and the main mailserver fqdn.
> > > >
> > > > And then set up the secondary box with an (higher number/lower
> > > > priority)
> > > > MX-record in DNS.
> > > >
> > > > Regards,
> > > >
> > >
> > > Ok, but what exactly happens ?
> > > I assume it goes like this:
> > >
> > > DNS record has two MX records with the Secondary set at lower
> > priority.
> > > The Primary server goes offline.
> > > E-Mail is then delivered to the secondary.
> > > The secondary holds it all in a queue and periodically attempts to
> > deliver it to the Primary but it never gives up trying.
> > > When the Primary comes back online, all the E-Mail is delivered
> > successfully.
> > >
> > > Is that correct?
> > >
> > > If so then there are a few things i'd like to know.
> > >
> > > 1. How would you see what E-Mail is in the queue?
> > >
> > > 2. If the Primary was going to be off for a long time and you needed
> > all that queued E-Mail to be delivered to a different server, how would
> > you go about that ?
> > Hi Darren,
> > 
> > Yes, your description is correct.
> > 
> > Answers to your questions:
> > 1, Well, log in as admin/root and run mailq as usual to see what's in
> > the queue. You can always tail /var/log/maillog as well.
> > 
> > 2, Change DNS of the main MX-pointer to the "new" mail-server and then
> > run sendmail -q (after flushing the DNS-cache) or just restart the
> > sendmail process.
> 
> 
> I've been playing with this and it does seem to work, however - will it only ever attempt to deliver to the server with the highest priority in the MX record? What about the others?
> Once an email is in the queue, will it only ever attempt to deliver to one fqdn from then on ?
> Can it not be changed ?
> 
Hi Darren,

No, it will try and deliver to the mailserver you entered in the Mail Server field. If you have a DNS round-robin situation or another solution
it will use that.

Regards,

Rickard Osser <rickard.osser at bluapp.com>
BluApp AB