Hi

Still building a nginx reverse proxy for my mail servers. Thanks to the community, I now have a secure connection between nginx and my backend mail server.

POP and IMAP are working well, from a MUA to my server.

I'm wondering how nginx can manage SMTP coonnections as it is used by both MUA and MTA.

A MUA must authenticate before sending mails; and my http_auth backend is able to authenticate users. More precisely, the authentication backend answers a server (auth-server / auth-port) depending on the domain of the destination email address.

Now I guess I have to accept incoming emails without authentication if the client is a MTA, but I don't find a obvious way to distingish a MUA and a MTA and let mu auth backend behave depending on that.

How to achieve that ?