If using RPC over HTTPs then only TCP port 443 else in MAPI connection TCP 135. Thanks & Regards Mitul Zaveri _____ From: exchangelist-bounce@xxxxxxxxxxxxx [mailto:exchangelist-bounce@xxxxxxxxxxxxx] On Behalf Of John Knijn Sent: Tuesday, June 05, 2007 12:12 PM To: exchangelist@xxxxxxxxxxxxx Subject: [ExchangeList] ports used? Good morning, What TCP and/or UDP ports are used during communication between Outlook 2003 and Exchange Server 2003? Outlook is configured in using ''Microsoft Exchange Server''. Thanks in advance. John