Exchange Server 2003 Firewall Ports

The following table lists various protocols and their associated ports that might be used in an Exchange implementation.

Protocol	Description	Ports
SMTP	Used to communicate with mail servers and by POP3 and IMAP4 clients to send mail. Note: SMTP with SSL is rarely used.	TCP 25 Using SSL, TCP 26
POP3	Used to retrieve mail from an Exchange Server. Disabled on the Exchange server by default.	TCP 110 Using SSL, TCP 995
IMAP4	Used to retrieve mail and other directories from an Exchange Server. Disabled on the Exchange server by default.	TCP 143 Using SSL, TCP 993
HTTP	Used by Outlook Web Access for mail access.	TCP 80 Using SSL, TCP 443
LDAP	Used to access information from Active Directory.	TCP and UDP 389 for Active Directory access TCP 3268 for Global Catalog access
NNTP	Used to retrieve information from Usenet servers on and enables sharing news group public folders.	TCP 119 Using SSL, TCP 563
RPC	Used to establish an RPC connection (end point mapper) and also acts as an RPC client establishing sessions.	TCP 135 TCP 1024 and above (multiple ports are typically enabled)
DNS	When contacting Active Directory, a DNS server must be contacted for name resolution. The Exchange server uses DNS to find mail servers on the Internet	TCP and UDP 53
MTA	Used for X.400 connections or connections to Exchange 5.5 servers.	TCP 102
Kerberos	Used for communication and authentication with Windows 2003 servers.	TCP and UDP 88
IPSec	Used to secure server-to-server communications.	IP protocol 51 for AH IP protocol 50 for ESP UDP 500 for key exchange TCP and UDP 88 for Kerberos