[PLUG] How does having a secondary MX work?

[Steven Raymond]

Thank you so much for your help on this- it was exactly what I was looking
for.  Works great!



> * Steven Raymond <stever at woo-hoo.com> [020914 21:33]:
>> 2)  Must you have all the existing user accounts receiving mail on
>> primary MX server also exist on the seconary MX server?  In my
>> testing, sending mail to existing-user at primarymx if they do not have a
>> local user account on secondary MX server results in bounced with
>> "user unknown".
>
> Sounds like your secondary mx server is configured as final destination
> for your domain, rather than as a secondary mx.
>
> If you want to set up "mail2.woo-hoo.com" as a secondary mx for the
> "woo-hoo.com" domain, then in your postfix main.cf:
>
> mydestination = $myhostname, localhost
> # Note - don't include $mydomain or woo-hoo.com in mydestination!
>
> relay_domains = $mydestination, woo-hoo.com
>
> This says you'll rely mail for woo-hoo.com, but you're not the final
> destination for it.
>
> When your primary is down, mail for woo-hoo.com will queue up on the
> secondary, but won't be delivered to local users in the mail spool file
> or whatever (unless it's addressed to user at mail2.woo-hoo.com).
>
> The mail will stay in the deferred queue on the secondary, and it will
> keep trying to relay it on to your primary until the primary comes back
> up and it can deliver it. Note that the longer your primary is down, the
> longer the secondary will wait between attempts to deliver it up to a
> configurable maximum, so don't get nervous when it doesn't deliver it
> immediately when the primary comes back up.
>
> You don't need to duplicate accounts on the secondary from the primary
> this way.
>
> --Stafford
>
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