The Subscription Manager add-in (SUM) is designed for the automatic adding/deleting subscribers to/from Microsoft Outlook 2000, 2002/XP and 2003 mailing lists based on special e-mail messages from them (requests). A request is a standard e-mail message that contains a command for SUM in its "Subject" field. Subscription Manager is the first mailing list management software for Microsoft Outlook.

SUM is capable of processing "subscribe", "unsubscribe" and "help" requests. When a subscribe or unsubscribe request is received, the user is added to or deleted from the distribution list specified in the request. Upon receipt of a help request, a message with information about the current subscription status and request sending rules is sent to the user. The adding to the distribution list can be made both with obtaining confirmation from the user and without it.

Once a request is processed, SUM sends an auto-reply with information about the processing result. Auto-replies are created based on Outlook templates using special macros (expressions that are automatically replaced when sending a message). You can make any desired changes to the appearance of SUM auto-replies by changing the auto-reply templates.

Since 1.1 version, Subscription Manager also supports mailing lists with subscription confirmation to exclude subscriptions from fake and other emails. And now Subscription Manager supports most features of a standalone product for mailing list management.