A user of ours is using the send as attachment option within Excel 2003 (SP2)
to send one of his spreadsheets on a daily basis. But for some reason, the
e-mails generated in Excel are always sent from one of his department
mailboxes, not his personal mailbox. I couldn't find any options within Excel
that automatically selects a mailbox to use, this occurs regardless if MS
Outlook is running and it never prompts for a MAPI profile to be used for the
e-mail.

How do I set the default mailbox to use for Excel?