You can create signatures for your email messages. Your signature can include your name and additional closing text to the maximum number of characters that your account allows.
For example, your signature could read:
John Smith
Vice President of Engineering
Widgets Division
Acme Corporation, Inc.
303-555-1212 x111
john.smith@example.com
If you create multiple identities, you can create different signatures and assign them to specific addresses. See Mail Identities.
Open Preferences and select the Signatures tab.
Because you can have more than one signature, in the Signature Name field give your signature and identifiable name.
In the Signature text box, type the signature information exactly as you want it to appear in your messages.
In the Using Signatures section, select where the signature should be placed in your messages. Select Above included messages to add your signature at the end of the your composed, replied to, or forwarded text. Select Below included messages to add the signature at the end of the message.
Click Save.
To apply this signature to your account name, go to the Accounts tab and in the Signature field, select the Signature Name from the drop down.