Different IP for Email

There is no easy way to achieve this as postfix does not has such a setting. You can e.g. setup a virtual machine with a separate ispconfig installation or you try to add listeners for each IP separately in postfix master.cf instead of the global port 25 listener, but this will only affect incoming email and not outgoing.

 

Postfix does support this, we have a single server (debian wheezy, non-ispconfig) using separate ip addrs for a couple domains (incoming and outgoing).

The outgoing piece uses sender_dependent_default_transport_maps to select the default transport according to the sender address, eg. set this in main.cf

Code:

sender_dependent_default_transport_maps = texthash:/etc/postfix/sender_dependent_default_transport_maps

then create /etc/postfix/sender_dependent_default_transport_maps with:

Code:

@dom1.com  dom1_smtp
@dom2.com  dom2_smtp
DUNNO

Then you create dom1_smtp and dom2_smtp transports that specify a different smtp_bind_address option, eg. in master.cf:

Code:

dom1_smtp      unix  -       -       -       -       -       smtp
    -o smtp_bind_address=x.x.x.x

dom2_smtp      unix  -       -       -       -       -       smtp
    -o smtp_bind_address=y.y.y.y

The incoming pieces are handled similarly, ie. multiple transports created to listen on each address and set a few options differently.

For another option, I believe you can accomplish the same thing with postfix instances as well, but I don't have a working example offhand.

 

One other thing that might be useful if someone were to incorporate such a config into ispconfig, we actually set variables with the bind IP addresses and use those in the transport definition. Eg. in main.cf:

Code:

dom1_smtp_bind_address = x.x.x.x
dom2_smtp_bind_address = y.y.y.y

And in master.cf:

Code:

dom1_smtp      unix  -       -       -       -       -       smtp
    -o smtp_bind_address=$dom1_smtp_bind_address

dom2_smtp      unix  -       -       -       -       -       smtp
    -o smtp_bind_address=$dom2_smtp_bind_address

You can then use postconf -e to set/change the ip address, rather than parsing master.cf (I don't know how how ispconfig handles that, it may or may not be easier).