When using the full functionality of Microsoft Small Business Server 2003 – it is necessary to open or forward ports within your router config. Port forwarding is needed to allow your SBS server to be ‘visible’ from the internet, and to allow incoming connections such as email, or remote web workplace. The following ports are required :

SMTP 25 – Simple Mail Transfer Protocol
HTTP 80 – Home Page Web
SSL 443 – Home Page Web Secured
HTTP2 444 – Second SSL Secured on alternate port for SharePoint
PPTP 1723 – VPN Connections
RDP 3389 – Remote Desktop Protocol (only needed for direct access, if using RWW website, only 4125 is needed)
RWW 4125 – Remote Web Workplace

If using Outlook over HTTP (also called Outlook Anywhere) the above ports are all that are required, however – if you have any users who still use the ‘original’ iPhone or users who require POP email – the following port forward are needed:

POP3 110 – If using POP3 mail connections
IMAP 143 – iPhone 1st Generation
IMAP SSL 993 – Even better for iPhone 1st Generation