From MozillaZine Knowledge Base

A signature is a block of text that is added automatically when you compose a new mail message or reply.

You can include a signature for each of your Mozillla Suite/SeaMonkey Mail account identities. Each signature can be plain text or HTML and is stored in a separate file on your computer. Any signature file can be used by more than one mail account identity.

1. In Mail, go to "Edit → Preferences → Mail & Newsgroup Account Settings".
2. Select a mail account identity.
3. Enter your signature into the textbox as described in more detail in the Thunderbird article.
   • Check "Use HTML" if the text you entered contains formatting using HTML markup.
4. Alternatively, you can create the signature in a file:
   1. Create a text or HTML file with your signature and store it on your hard drive.
   2. Check "Attach this signature from a file instead".
   3. Click "Choose..." to locate the signature file you previously created.

Note that the textbox and "Use HTML" option to directly enter the signature into the account settings was not available in versions prior to SeaMonkey 2.0, older releases only provided the option to add a signature from a file.

See also

• Signatures - Thunderbird (this article is much more detailed and the procedures are essentially the same for SeaMonkey)