you could create a small outbound only smarthost elsewhere..
somewhere that does let you make outbound connections on port 25.
aws / digital ocean / hetzner et will let you do this, although you may need to have an account with them for a couple of months before they will allow you to open port 25 outbound.
then you can configure the smarthost to accept mail relayed mail on a custom port, and configure each webserver to relay to that custom port, that way, even if your current hosting blocks port 25, you can still relay out to the smarthost.
although, by default, enhance should be using authorised relay access on the submission port (587) which wouldn't normally be blocked by your hosting provider, so the only issue really is allowing 25 outbound from the smarthost.
the control server uses ports 50000, 50003, and 50004 to communicate with the other servers, although these ports have nothing to do with email relaying..
all the email stuff uses the standard ports.. 25 smtp, 110 pop3, 143 imap, 993 imaps, 995 pop3s, 465 smtps, 587 starttls. 2525 and 3535 are sometimes used as alternative port numbers.
