When you use an Edge Server in your Exchange 2007 environment, you’ve to open some ports. Let’s open the right ports:
Incoming Traffic:
SMTP – TCP 25 – from the Internet
SMTP – TCP 25 – from the Edge Server to the Hub Transport Server
Outgoing Traffic:
SMTP – TCP 25 – from the Edge Server to the Internet
SMTP – TCP 25 – from the Hub Transport Server to the Edge Server
Secure LDAP – TCP 50636 – from the Hub Transport Server to the Edge Server
DNS – UDP 53 – from the Edge Server to the Internet
RDP – TCP 3389 – from the Hub Transport Server to the Edge Server