An email signature is a word or phrase that is added to the bottom of your outgoing email messages. A signature can be as simple as J. Smith, for example, or as complicated as a lengthy quote from a Shakespeare play.
To create new signature:
Click the Preferences link above the blue Web Mail bar at the top of the Web Mail page.
Click the Sending & Replying tab.
At the bottom of the page, click the Signatures link to open the Signatures preferences page.
Name your new signature something you'll recognize later (like "Informal signature" or "Work").
Type your signature.
If you want this signature to be added by default to every message, check the Set As Default box. (You can always change the signature while writing a message.)
See also: Adding a signature to an email message