Most Popular Extensions
Header Tools Lite Requires Restart
Allows to modify the header and the source of messages
Menu Wizard Requires Restart
Customize menus : Helps removing, moving and renaming menus and menu items
Colorize important menu for ease of use! (use Style (CSS))
Change or disable any of used keyboard shortcuts
Support: Firefox, Thunderbird and SeaMonkey
Year view Requires Restart
Year view for calendar.
Join-NG Requires Restart
Join partial messages. Somewhat similar to MS Outlook Express "combine and decode".
FlashGot Mass Downloader Requires Restart Featured
Download all the links, movies and audio clips of a page at the maximum speed with a single click, using the most popular, lightweight and reliable external download managers.
Folderpane Tools Requires Restart
Allows for customization of the folder pane. Accounts can be rearranged and the startup folder can be chosen.
This extension enables true full screen mode in SeaMonkey for HTML5 video players, slide-shows, etc. and also for full screen invoked manually with the F11 key.
Quote Colors Requires Restart
Quote Colors allows you to select text and background colors of different quote levels which are applied when reading or printing mail/news messages. Additionally, you can choose between graphical and traditional plain text quoting display mode.
Reinstates the extensions.checkCompatibility preference without respect to the current application version.
Show contact photo and other info from Local Dir, Addressbook, LDAP, Facebook, LinkedIn, Flickr, Gravatar etc
Simple Locale Switcher Requires Restart
An easier management of the user interface language
ThreadKey Requires Restart
Strike the 'T' key to sort messages by thread, strike the 'U' key to sort them unthreaded again, just like the 'G' key switches to Grouped By Sort view.
Adds two columns to the list of mails. One shows an indicator wether a mail is incoming or outgoing, the other shows the sender or the recipient of the mail respectively...
Adds icons to buttons and/or menus.
Image Zoom Requires Restart
Adds zoom and rotation functionality for images...
SeaTab-X-2 Requires Restart
Adds Firefox-style tab closers into SeaMonkey.
Fight the text ads! Element Hiding Helper is a companion extension for Adblock Plus meant to make creating element hiding rules easier.
The first and only download manager/accelerator built inside Firefox!
Saved Password Editor Requires Restart
Adds the ability to create and edit entries in the password manager.
Flexible Identity Requires Restart
Selects an identity based on the recipients list when sending an email