relay to internal servers not working as expected

[Gambix]

I have domainA.com configured with external MX pointing to pmg . The mail is received by pmg fine. It then has to be forwarded /relayed to an internal server. In the transport config, this domain is setup to use MX records.
MX records point to two servers:
domainA MX 10 internal1.com
domainA MX 50 internal2.com

I would expect that:
- pmg should try first internal1.com (higher priority), instead it tries first internal2.com. Why ?
- if internal2.com is down, mail should be relayed to internal1.com, instead it stays there. Why ?

TIA for any help

Michelangelo

 

[Gambix]

SOLUTION found

I firewall was blocking connections from pmg to internal server (internal1.com) on port 25, so it was failing over to internal2.com

This explains both of the questions above