First, let's talk about SeaMonkey, a free, open-source, cross-platform Internet Software Package (including a Web browser, email and newsgroup client, and an HTML editor, an IRC chat and web development tool) created by the Mozilla Foundation and then developed by its SeaMonkey project leader team.
The latest version of SeaMonkey 2.25 is recently released based on Firefox 28. This version has made a lot of fixes and a lot of new features. Read the Information Release Notes.
Installation commands (supported systems: Ubuntu 12.04, 12.10, 13.10, 14.04, Linux Mint 16, Linux Mint 14, Linux Mint 13, and Elementary OS 0.2 ):
Echo-e "ndeb http://downloads.sourceforge.net/project/ubuntuzilla/mozilla/apt all main" | sudo tee-a/etc/apt/sources. list>/dev/null
Sudo apt-key adv -- recv-keys -- keyserver keyserver.ubuntu.com C1289A29
Sudo apt-get update
Sudo apt-get install seamonkey-mozilla-build