spockdude Wrote:
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> I have several users using the same mail host (smtp.example.com) to
> send outbound email using authentication. I would like to split it up
> into several outbound servers and assign specific users to specific
> mail servers without having to change the mail host information in
> each user's email client. Can Nginx do this or does it always just
> spread that traffic between all backend servers?


It seems this list is not very active, but I'll go ahead and answer my own question. It *does* appear that the above functionality is supported according to this page:

https://www.nginx.com/resources/admin-guide/mail-proxy/

It says "If authentication is successful, the authentication server will choose an upstream server and redirect the request."

If I'm understanding this correctly, I just need to create an authentication server that instructs Nginx which upstream server to send the request to based on the user's credentials.