[BlueOnyx:01608] Re: Secondary Mail Server

[Darren Wolfe]

>  
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InterSys Micronics Ltd 
Darren Wolfe 
 tel: 01253 716800 fax: 01253 782879 
e-mail: darren at intersys-group.com 
www: http://www.intersys-group.com 
291 Clifton Drive South 
St. Annes-on-Sea, Lancashire, FY8 1HN
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-----Original Message----- 

> From: blueonyx-bounces at blueonyx.it [mailto:blueonyx-
> bounces at blueonyx.it] On Behalf Of Rickard Osser
> Sent: 02 July 2009 14:11
> To: BlueOnyx General Mailing List
> Subject: [BlueOnyx:01559] Re: Secondary Mail Server
> 
> 
> 
> On Thu, 2009-07-02 at 12:46 +0100, Darren Wolfe wrote:
> > > From: blueonyx-bounces at blueonyx.it [mailto:blueonyx-
> > > bounces at blueonyx.it] On Behalf Of Rickard Osser
> > > Sent: 02 July 2009 11:34
> > > To: BlueOnyx General Mailing List
> > > Subject: [BlueOnyx:01555] Re: Secondary Mail Server
> > >
> > > On Thu, 2009-07-02 at 11:23 +0100, Darren Wolfe wrote:
> > > > Hi,
> > > >
> > > >
> > > >
> > > > 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 ?