We had several problems with smartermail product. Could you look at them and try to solve.
1. If mail filtered by domain filter and copied to my account, my account filter doesn't work on this mail.
2. If I have smartermail mail account, I could send mail throw smtp as another person from outlook or other mail client.
3. Active directory username filed doesn't work in user settings if use active directory authentication. Example: I want mail firstname.lastname@example.org to authenticate with email@example.com in AD.