Can someone help me a bit with nginx?

[anaxagoras]

so i already have a reverse proxy on my docker stack, i'm running traefik.

However I want to put nginix as a reverse proxy in front of it.  I basically want to reverse proxy my mail server and have it split off on opnsense than rely on my docker stack being up.

so my goal is as follows
1.) Any traffic that is going to *.domain1.com to have nginix relay that traffic to my dockerhost to let traefik figure it out.
2.) any traffic that is going to mail.domain2.com have nginix relay that to my mail host which is a separate server.

I have never used nginix and using the opnsense plugin has me a little confused since none of the write ups i've found translate over 100%