You must specify the external IP address in the main.cf proxy_interfaces
parameter, otherwise Postfix will not know that it is MX host, and
mail will loop.

        Wietse

Kenneth Maupin:
> Hi,
>
> We're designing a new mail system which sits behind a load balancer.
> One component of this system is a set of hosts dedicated to queuing
> mail for domains to which we offer secondary MX. Our intent is to use
> the load balancer to present a single routable IP address to the
> outside world regardless of how many hosts reside behind it. The
> queuing hosts are configured with non-routable IP addresses visible to
> the load balancer only. Domains for which we offer secondary MX will
> refer to the routable address in their MX records. When the primary
> MX host is down, mail will wait on our queuing hosts until the primary
> comes back up.
>
> We'd like to use the load balancer front end instead of round-robin MX
> records because concealing the queuing hosts behind the load balancer
> allows us to remove hosts from service and add new hosts without
> modifying DNS. This also simplifies DNS considerably, as we'll have a
> single secondary MX record for all domains instead of one for every
> queuing host. We currently provide secondary MX for over 1,000
> domains, so this is a significant savings.
>
> The network diagram, example DNS records, and an abbreviated Postfix
> configuration for this system are as follows...
>
>
> ________________________________________
> NETWORK DIAGRAM
>
>
> Internet
> |
> 206.26.36.1 (mxqueue.easystreet.com)
> |
> +---------------+ ROUTABLE NETWORK
> - - - -| Load balancer |- - - - - - - - - - - - - - - - - - - - - - -
> +---------------+ NON-ROUTABLE NETWORK
> |
> +-----------------+
> | |
> 192.168.0.1 192.168.0.2 (mxqueue01. and
> mxqueue02.easystreet.com)
> | |
> +-----------+ +-----------+
> | mxqueue01 | | mxqueue02 |
> +-----------+ +-----------+
>
>
> ________________________________________
> EXAMPLE DNS RECORDS
>
> domain.com. 86400 IN MX 20 smtp.domain.com.
> domain.com. 86400 IN MX 80
> mxqueue.easystreet.com
> mxqueue.easystreet.com. 86400 IN A 206.26.36.1
>
>
> ________________________________________
> ABBREVIATED POSTFIX MAIN.CF CONFIGURATION
>
> myhostname = mxqueue01.easystreet.com
> mydestination = $myhostname, mxqueue.easystreet.com
> inet_interfaces = $myhostname
> relay_domains = hash:$config_directory/relay_domains
> alias_maps = hash:$config_directory/aliases
> alias_database = $alias_maps
>
>
> We're trying to determine the correct Postfix configuration for this
> network design. In our experiments, mail sent to domain.com arrives
> on one of the MX queuing hosts as expected if smtp.domain.com is down,
> but Postfix immediately tries to redeliver it to
> mxqueue.easystreet.com because it doesn't realize that it is acting as
> mxqueue.easystreet.com. The result is a mail loop.
>
> Our question is this: can Postfix be configured into thinking it
> should queue mail as if it is mxqueue.easystreet.com despite the host
> having no network interfaces configured with this name? Adding
> mxqueue.easystreet.com to $mydestination has no apparent effect.
>
> Any advice would be greatly appreciated. Thanks!
>
>
> - - - - - -*- - - - - -
>
> - Kenneth Maupin EasyStreet Online Services,
> Inc. -
> - Senior Systems Engineer Beaverton,
> Oregon -
> - maupineasystreet.com
> http://easystreet.com/ -
> - - - - - -*- - - - - -
>
>

• Messages sorted by: [ date ] [ thread ] [ subject ] [ author ]