Persistent or keepalive connections to SMTP backends

[kayrus]

Is it possible to reuse an established SMTP connection for multiple independent auth sessions?

My SMTP backend server allows limited connections per one IP and I'm looking for a solution to reuse TCP connection for multiple independent sessions.

[emersion]

I'm not aware of any way to do this. RFC 4954 states that once an AUTH command has been issued, no more AUTH commands can be sent for the lifetime of the SMTP session.

[kayrus]

Thanks for update. I'm closing an issue then.