Zimbra cluster and postfix smtp_bind_address

[Lebha]

Hi everyone,

I have a Zimbra cluster setup like this:

node primary.example.com, IP 10.0.0.2
node secondary.example.com, IP 10.0.0.3
cluster service name mail.example.com, cluster service IP 10.0.0.4

I would like to setup postfix so that it uses the cluster service IP address 10.0.0.4 and not the cluster node's own IP address (10.0.0.2) when it's sending mail to outside recipients.

Elsewhere it is said that one shouldn't use postfix's smtp_bind_address to achieve the desired end result. Is there any other way to do it?

[Lebha]

Just to explain why I think this is important:

when postfix opens an SMTP connection to, say, hotmail.com to send mail, it uses the IP 10.0.0.2. Then it says "EHLO mail.example.com" to initiate the SMTP session. hotmail checks the sending server in several ways, and one of them is a reverse dns check. 10.0.0.2 doesn't resolve to mail.example.com but to primary.example.com. This makes the sending server suspicious to hotmail and the messages sent are more likely to end up in the hotmail recipients' "Junk" folder.

This is just an example, and you could replace hotmail with any big ISP/mail provider. This is a real problem for us.

[Klug]

I'm not following you here.

What kind of cluster are you using, RHCS ?

Postfix should bind to the virtual IP, just like any other Zimbra service (mailboxd, amavisd, etc).

[Lebha]

It is indeed RHCS, installed exactly as documented in Zimbra Single Server Cluster Installation Guide.

[Klug]

And using RHCS, postfix does not bind to the virtual IP ???

[Lebha]

Originally Posted by Klug

And using RHCS, postfix does not bind to the virtual IP ???

That's exactly the case! It uses the hosts own ip instead.

[Klug]

I've just checked with a message set by one customers' cluster (running 4.5.10) : postfix "speaks" through the virtual IP.

[Lebha]

Originally Posted by Klug

I've just checked with a message set by one customers' cluster (running 4.5.10) : postfix "speaks" through the virtual IP.

That's weird! I'm still running 4.5.9, but that shouldn't make any difference, should it?

[Lebha]

Originally Posted by Klug

Postfix should bind to the virtual IP, just like any other Zimbra service (mailboxd, amavisd, etc).

I think postifix binds to IP_ADDR_ANY, at least on my site it is listening on:
- localhost (127.0.0.1)
- server ip address (10.0.0.2)
- cluster service address (the "virtual IP", 10.0.0.4)

How to make postfix use the virtual IP when talking to outside, without generating problems referred to in this post?