7 Things You Need to Know About SharePoint Services

#5: Exchange Needs to Accept SMTP Email from SharePoint
SharePoint relieves users from the pain of periodically checking various pages on the server to find out whether new content has been added or updated to Share-Point. To do so, it emails alerts whenever content of interest to the user changes (e.g., someone created a new task or changed an event on the calendar). If users complain that they aren't getting these alerts, you're looking at one of two probable causes: The Exchange server is refusing to accept these SMTP alerts, or you haven't configured SharePoint with the address of your Exchange server or other SMTP server. To configure SharePoint to send alerts, click the Configure default e-mail server settings link in SharePoint Central Administration and fill in the Outbound SMTP server and From e-mail address fields as appropriate. Specify the DNS name or IP address of an SMTP server that's reachable from your SharePoint server, and make sure the SMTP server can route email to internal employees as well as external addresses on the Internet (if your SharePoint site will be accessible to outside business partners such as consultants, contractors, or clients). Specify an email address that Share-Point can use as the From address for all alert emails. Next, make sure your SMTP server can accept anonymous SMTP connections from your Share-Point server. . . .