SeaMonkey Mail is a traditional e-mail client that includes support for multiple accounts, junk mail detection, message filters, HTML message support, and address books, among other features. It shares code with Mozilla Thunderbird; both Thunderbird and SeaMonkey are built from Mozilla's comm-central source tree.
SeaMonkey Composer is a WYSIWYG HTML editor. Its main user interface features four tabs: Normal (WYSIWYG), HTML tags, HTML code, and browser preview. The generated code is HTML 4.01 Transitional. SeaMonkey Composer is no longer actively maintained, but the underlying editor code is shared with the Mail component.