Seamonkey is a Mozilla product which includes a web browser (based on Firefox), an email client (based on Thunderbird), an HTML editor, and a chat.
Ranked in these QuestionsQuestion Ranking
Pro Not just an e-mail client
Seamonkey is more than just an e-mail client as it is a full featured web browser as well. This makes for a good app to use for those that dislike having many different apps on their devices as it is a bit like an all in one solution.
Pro Auto imports setting from Thunderbird
For those that would be making the switch from the Thunderbird e-mail client setup is quite easy with Seamonkey as it auto imports all previous Thunderbird settings.
Con Permanent CPU usage
Seamonkey permanently uses CPU (quite a few percents on a Intel i7). On a laptop this causes the fan to run (which make noise) and the battery to lasts less time.