Mail rule to work on mails sent from mail-in databases

Users want to move certain emails to certain folders based on the sender of the email. This works as long as the mails come from individual users. However, when the mail comes from a mail-in database, there will be a problem. In the Inbox's Who column, the mail looks like it is coming from the mail-in database, however in reality it is coming from the user who sent it, thus the From field will be the user's email address. The string in the Who column, which in this case would be the name of the mail-in db, is in the dspFrom field and therefore the mail rule that has a condition on the sender, will not recognise it. We wish to have a way to create a mail rule with condition on the displayed sender, thus on the mail-in database's name. Thank you.