The Hybrid mode has nothing to do with Proxy vs Regular SMTP. It should work even with the Proxy Server. Could you please elaborate on what do you mean by "It does not work"? The only difference between Hybrid and Firewall mode is the use of POP3/IMAP servers in Xeams. In Hybrid mode, Xeams will create a user repository that is accessed by POP3/IMAP servers.

So are you trying to connect to either POP3 or IMAP servers on Xeams and are they not working?

BTW, regardless of the mode (hybrid or firewall), you should switch to the regular SMTP server. Refer to https://www.xeams.com/SwitchingProxy2Regular.htm for instructions as well as rationale for switching.