This dialog makes it possible for you to easily create default and per-domain message signature text. If the default signature text is present it will be appended to all messages sent from all local users unless there is alternate text supplied for the user's specific domain. When domain-specific text if found, that is given priority over the default text. Domain signatures are always be added to the bottom messages. However, for mailing list messages using a footer, the footer will be added below the domain signature.
You can also use the Account Editor's Signature feature to add individual signatures for each Account. Account signatures will be added just before Domain Signatures.