An event sink that is registered against a mailbox does not work in Exchange Server 2003

After you register an information store event sink against a user's Microsoft Exchange Server 2003 mailbox, when you send a message to that user, the event sink does not perform the requested actions.

This problem occurs if the user's mailbox contains a forward slash (/) character in the mailNickname property. For example, this problem occurs if the user's mailbox name is similar to User/Name. In this scenario, the registered event sink cannot obtain a valid URL for an item in the user's mailbox.

This problem might occur when one or more of the following conditions are true:

• You configure a mailbox name that contains a forward slash character in Microsoft Exchange Server 5.5 and then upgrade to Exchange 2003.
  
  Note A forward slash character is permitted in an Exchange 5.5 mailbox name.
• You add a forward slash character to a user's mailNickname property by using the ADSI Edit tool.
• You add a forward slash character to a user's e-mail alias by using the Active Directory Users and Computers tool.

Exchange 2003 should replace the forward slash character with an underscore (_) character. When the mailbox name contains a forward slash character, the URL to an item in that mailbox is not valid.

To work around this problem, remove the forward slash character from the mailbox name.

Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.