This is very useful to any Administrator, so here it is:

( The credits for the great picture goes to EighTwOne.com )

And the complete PORT LIST:

Transport Servers 
Hub Transport server to Hub Transport server: 25/TCP (SMTP)
Hub Transport server to Edge Transport server: 25/TCP (SMTP)
Edge Transport server to Hub Transport server: 25/TCP (SMTP)
Edge Transport server to Edge Transport server: 25/TCP SMTP
Mailbox server to Hub Transport server via the Microsoft Exchange Mail Submission Service:135/TCP (RPC)
Hub Transport to Mailbox server via MAPI: 135/TCP (RPC)
Unified Messaging server to Hub Transport server: 25/TCP (SMTP)
Microsoft Exchange EdgeSync service from Hub Transport server to Edge Transport server:50636/TCP (SSL)
Active Directory access from Hub Transport server: 389/TCP/UDP (LDAP), 3268/TCP (LDAP GC), 88/TCP/UDP (Kerberos), 53/TCP/UDP (DNS), 135/TCP (RPC netlogon)
Active Directory Rights Management Services (AD RMS) access from Hub Transport server:443/TCP (HTTPS)
SMTP clients to Hub Transport server: 587 (SMTP) / 25/TCP (SMTP)

Mailbox Servers

Active Directory access: 389/TCP/UDP (LDAP), 3268/TCP (LDAP GC), 88/TCP/UDP (Kerberos), 53/TCP/UDP (DNS), 135/TCP (RPC netlogon)
Admin remote access (Remote Registry): 135/TCP (RPC)
Admin remote access (SMB/File): 445/TCP (SMB)
Availability Web service (Client Access to Mailbox): 135/TCP (RPC)
Clustering: 135/TCP (RPC)
Content indexing: 135/TCP (RPC)
Log shipping: 64327 (customizable)
Seeding: 64327 (customizable)
Volume shadow copy service (VSS) backup: Local Message Block (SMB)
Mailbox Assistants: 135/TCP (RPC)
MAPI access: 135/TCP (RPC)
Microsoft Exchange Active Directory Topology service access: 135/TCP (RPC)
Microsoft Exchange System Attendant service legacy access (Listen to requests): 135/TCP (RPC)
Microsoft Exchange System Attendant service legacy access to Active Directory: 389/TCP/UDP (LDAP), 3268/TCP (LDAP GC), 88/TCP/UDP (Kerberos), 53/TCP/UDP (DNS), 135/TCP (RPC netlogon)
Microsoft Exchange System Attendant service legacy access (As MAPI client) 135/TCP (RPC)
Offline address book (OAB) accessing Active Directory: 135/TCP (RPC)
Recipient update to Active Directory: 389/TCP/UDP (LDAP), 3268/TCP (LDAP GC), 88/TCP/UDP (Kerberos), 53/TCP/UDP (DNS), 135/TCP (RPC netlogon)

Client Access Servers

Active Directory access: 389/TCP/UDP (LDAP), 3268/TCP (LDAP GC), 88/TCP/UDP (Kerberos), 53/TCP/UDP (DNS), 135/TCP (RPC netlogon)
Autodiscover service: 80/TCP, 443/TCP (SSL)
Availability service: 80/TCP, 443/TCP (SSL)
Outlook accessing OAB: 80/TCP, 443/TCP (SSL)
Outlook Web App: 80/TCP, 443/TCP (SSL)
POP3: 110/TCP (TLS), 995/TCP (SSL)
IMAP4: 143/TCP (TLS), 993/TCP (SSL)
Outlook Anywhere (formerly known as RPC over HTTP ): 80/TCP, 443/TCP (SSL)
Exchange ActiveSync application: 80/TCP, 443/TCP (SSL)
Client Access server to Unified Messaging server: 5060/TCP, 5061/TCP, 5062/TCP, a dynamic port
Client Access server to a Mailbox server that is running an earlier version of Exchange Server:80/TCP, 443/TCP (SSL)
Client Access server to Exchange 2010 Mailbox server: RPC
Client Access server to Client Access server (Exchange ActiveSync): 80/TCP, 443/TCP (SSL)
Client Access server to Client Access server (Outlook Web Access): 80/TCP, 443/TCP (HTTPS)
Client Access server to Client Access server (Exchange Web Services): 443/TCP (HTTPS)
Client Access server to Client Access server (POP3): 995 (SSL)
Client Access server to Client Access server (IMAP4): 993 (SSL)
Office Communications Server access to Client Access server: 5075-5077/TCP

Unified Messaging server data paths

Active Directory access: 389/TCP/UDP (LDAP), 3268/TCP (LDAP GC), 88/TCP/UDP (Kerberos), 53/TCP/UDP (DNS), 135/TCP (RPC netlogon)
Unified Messaging Phone interaction (IP PBX/VoIP Gateway): 5060/TCP , 5065/TCP, 5067/TCP (unsecured), 5061/TCP, 5066/TCP, 5068/TCP (secured), a dynamic port from the range 16000-17000/TCP (control), dynamic UDP ports from the range 1024-65535/UDP (RTP)
Unified Messaging Web Service: 80/TCP, 443/TCP (SSL)
Unified Messaging server to Client Access server: 5075, 5076, 5077 (TCP)
Unified Messaging server to Client Access server (Play on Phone): Dynamic RPC
Unified Messaging server to Hub Transport server: 25/TCP (TLS)
Unified Messaging server to Mailbox server: 135/TCP (RPC)

If you encounter any problems feel free to comment / contact me