I need to be able to specify what interface Postfix will use to deliver outbound mail on. What I am doing is setting up an SMTP gateway to deliver mail from different, unrelated groups. I plan to setup a separate instance of Postfix for each group to receive mail, and each instance will need to deliver on its own virtual interface.

The reason I need them separate is so that if one of the groups misbehaves and gets the server blacklisted, I don't want any of the other groups affected. But I don't want to have to setup entirely separate servers or VMs if possible.

2 Answers 2


You're looking for smtp_bind_address and smtp_bind_address6. Details are available here.

  • It's customary when the answer is correct to click the little tick mark next to the answer! People are more likely to answer future questions if you acknowledge previous correct answers! Feb 11, 2011 at 18:23

Would inet_interfaces do what you want?

When inet_interfaces specifies just one IPv4 and/or IPv6 address that is not a loopback address, the Postfix SMTP client will use this address as the IP source address for outbound mail. Support for IPv6 is available in Postfix version 2.2 and later.

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