I'm currently looking at options for a mail server proxy that will select an upstream server based on the user that was authenticated. I didn't see anything like that mentioned in the NGINX guide for configuring a mail proxy server, but is there anyway that this can be done with NGINX? If not, is there some other proxy solution that would allow this to be done?
I see that NGNIX allows several methods for selecting the load balancing server, but I didn't see any that would allow the server to be selected by the authenticated user. (The link here is for HTTP load balancing, but I'm guessing the same rules are allowed for SMTP traffic as well.)
If not possible with NGNIX, is this possible with HAproxy?