OT: Backup MX

[Green, Rodney]

Jon Radel wrote:
> Green, Rodney wrote:
>   
>>
>> Green, Rodney wrote:
>>     
>>> Green, Rodney wrote:
>>>       
>>>> Hello,
>>>>
>>>> We recently had a day of downtime for our Internet connection. We
>>>> don't have a backup MX to queue mail while our  mail server is
>>>> unreachable.
>>>>
>>>> My question is this. If I were to get a DSL connection setup and
>>>> connect a backup DNS server and backup MX server, would there be a way
>>>> for users to access incoming mail that is queued on the backup MX?
>>>> How is something like this normally handled? We rely on e-mail here and
>>>> need some sort of backup plan if our main connection goes down.
>>>>
>>>> Thanks for any suggestions.
>>>> Rod
>>>>
>>>>
>>>>
>>>>         
>>> Just to add a little more information.. I'm using postfix as our MTA
>>> and of course MailScanner.
>>>
>>>
>>>
>>>
>>>       
>> Replying to my own post yet again. :-)
>>
>> I think my answer is in how DNS and MX records work. I guess I was
>> confused by the term "backup mx." It looks like I would need to setup a
>> duplicate mail server on the DSL connection, with a different FQDN, of
>> course, and set it up as a final destination for mail. Then in DNS I
>> would set up that new server with a lower priority than the normal
>> server. If the primary server is down mail should then be delivered to
>> the server on the DSL connection and be accessible to the users with a
>> simple configuration change. Does this sound correct?
>>
>>     
>
> No.  It sounds like a horrible mess.  Manually maintaining the same
> users on two independent servers.  A single user's mail split across two
> servers, with where a piece of mail sits depending on connectivity
> between the sender and your servers (your "backup" server would get some
> e-mail even if your main connection was nominally up, and it wouldn't
> *all* be spam).
>
> Easiest of all would probably be buying one of the turn-key boxes
> available that allows you plug in multiple ISP connections and handles
> all the connectivity tracking and fiddling with multiple NAT tables for
> you.  I suspect they come with explicit hints on how to setup your MX
> records to interop with their box.  (I'd give brand names if I could
> recall any at the moment.)
>
> Probably second easiest would be to simply multi-home your SMTP server,
> with an address from each ISP.  It would then accept connections across
> either connection.
>
> Another possibility would be to actually have a backup MX server, but
> make sure it could reach your mail server across a LAN connection so
> that it could forward incoming mail.  This one wouldn't help with the
> problem of off-site clients reaching the server across the Internet.
>
> Lots of choices, many of them driven by factors you've not covered here.
>
> --Jon Radel
>   

Ahh.. I didn't think of multi-homing the mail server. That seems like it 
might be the best option. I'll look
into doing that.

Thanks everyone!
Rod



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