I think it would be great to be able to resend an acknowledgment email to a donor/event participant when one is returned as a bad email address.  Recently we had a ticketed event that caused a lot of issues when the email address came back as a bad email address.  We had no way to resend the ticket to a new email without recreating the email in a different email service.

Providing a way to resend to a new address would really help with relationships and time restraints for our department.