external_mtas verified
Proxied sending addresses
Addresses that are not on the machine: the engine binds locally, connects to a proxy, and mail leaves from an address the proxy owns.
In detail
MailerQ's answer to sending from addresses a node does not have. The row says which local address to bind, which proxy host and port to reach, which protocol to speak, and which public range the proxy should present. This is the same problem our proxy gateway solves for PowerMTA, and it is worth comparing the two before building anything: MailerQ has the mechanism in the engine, ours is outside it. A customer with rented addresses is the case where this table stops being theoretical.