Returns the MAPI mail session number as a hexadecimal string (if there's an active session), or returns Null if there's no session. Read-only Variant.
Remarks
This property applies only to mail sessions created by Microsoft Excel (it doesn't return a mail session number for Microsoft Mail).
This property isn't used on PowerTalk mail systems.
Example
This example closes the established mail session, if there is one.
If Not IsNull(Application.MailSession) Then Application.MailLogoff