Purging your mug from Mail messages is easy, if you’re willing to live without a picture for your user account and Address Book card.

That’s a tricky one, but with a little work you can remove it. Mail automatically adorns your messages with the picture that you’ve set as your user-account picture. So all you need to do is change your account picture (System Preferences > Accounts > username > Picture), and Address Book will immediately start using the new picture on your personal card, as will Mail on your messages. To remove the picture rather than change it, open Address Book and select your personal card, then from the menubar select Card > Clear Custom Image. Now the system will use Apple’s generic user picture in the login window and System Preferences’ Accounts pane. Mail and Address Book will remain blank until you designate a new picture in Address Book or System Preferences > Accounts.

If you’re really embarrassed about that picture on your email messages, know that Address Book goes both ways - if your recipients have your old card in their Address Books, the offending user picture will automatically appear on messages from you. So drag your new, unadorned Address Book card into the message body and ask them to replace your old card with it.