#3 Persona support

[Simon Hay]

Allow the user to select a 'persona' - set of From:,
Reply-To: and signature - for each outgoing message.
Perhaps this could be intelligent, so, for instance, if
the To: field of a message is the From: address of one
of your personas, automatically use that persona when
replying. Also, the ability to specify the persona to
use for correspondance with each person in your
Contacts list would be useful.