To add an e-mail signature to all of your outgoing e-mail messages:

1. Click/Tap the Identity button in the top-right hand corner
2. Click/Tap the Settings menu option
3. Click/Tap the General tab on the left
4. Click/Tap on your name in the Identity field
5. Click/Tap the Insert this signature before quoted text in replies option
6. Type your e-mail signature into the text editor
7. Click/Tap the Update button to save your changes.