This extension allows multiple separate signatures to be attached to contacts, per contact and message type, i.e. letters and e-mails, each as plain text and HTML-formatted, as well as for mass mailings. Once created, those are available as tokens in each message and can be used within message templates.
When sending messages, those tokens are being replaced with the particular signature of the logged-in contact, or the creator contacts, when using mass mailings (which can be sent automatically by a cron job), respectively.