From Word Place:
E-Mail Workshop, from the developers of Yeah Write for Windows, makes it easy to broadcast e-mail messages and maintain an address list (in other words, E-Mail Workshop is designed for mass e-mailings).
E-mail Workshop comes with a full set of editing features, including a speller, character styles for bold, underline, italics, sub and superscripts, and paragraph styles for bullets, numbered lists, outlines, headings, and more. Eleven international dictionaries are included.
You can add addresses one at a time, or you can import them from text files. A message received with "Add" in the subject, automatically adds that address to the address list. A message received with "Unsubscribe" or "Remove" as the subject, automatically removes the address. Housekeeping tools are included for deleting duplicate and bad addresses and for verifying domain names. Bounced messages (messages returned with an error, like unknown host, unknown user, etc.) are processed automatically.