An signature is a body of text that is sent on the bottom of email's, which may contain location, contact details etc. [DEFAULT] is the default signature which is used, but you can create more and associate these with identities.

 

 

When you click the Edit link next to a signature, or click the New Signature button, you can then create the signature to be used. If you wish to include an image, just drag and drop a picture into the edit box.