SeaMonkey is a Mozilla project by means of which they offer the user an “all-in-one” solution to work on the Internet.
Being a Mozilla project, the Internet browser included in SeaMonkey is based on the popular Mozilla Firefox web browser.
In addition, the email client is based on the well known Mozilla Thunderbird email client.
It can import feeds, email accounts, bookmarks and other data from an existing installation of either Mozilla Thunderbird or Mozilla Firefox apps.
It can also be used as a replacement for both of them.
If you want to have everything that’s necessary when it comes to using the Internet, download SeaMonkey.