Most Popular Extensions
Header Tools Lite Requires Restart
Allows to modify the header and the source of messages
Dorando keyconfig Requires Restart
A modified Dorando's addon to rebind keyboard shortcuts. It is designed to be a drop-in replacement, keeping your old settings. (See details for upgrade instructions.)
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
QuoteCollapse Requires Restart
Collapse and expand quotes. Please see the extension homepage for further information.
Note that MozDev has shut down long ago (mailing list etc). Add-On homepage, source code and issue tracker are on GitHub, as linked on this page.
P7MON Requires Restart
Abilita la gestione alternativa degli allegati P7M
Smiley Fixer Requires Restart
Fixes Wingding Smileys in Outlook-generated emails
Toggle Word Wrap Requires Restart
Toggle word wrapping and PRE element wrapping in the message composition and HTML display windows, respectively.
Year view Requires Restart
Year view for calendar.
FolderFlags Requires Restart
Allows users to edit the flags Thunderbird sets on folders.
'Classic Toolbar Buttons' add-on restores old toolbar button ui (known from Fx 4-7 small view, Fx4-12 large view & Tb5-14) for current Firefox, Thunderbird and Seamonkey versions.
No Message Pane Sort by Mouse Requires Restart
No Message Pane Sort prevents accidental resorting of the message pane by disabling mouse button clicks on the column headers.
It is still possible to sort messages by ctrl-clicking the header.
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.
Join-NG Requires Restart
Join partial messages. Somewhat similar to MS Outlook Express "combine and decode".
Folderpane Tools Requires Restart
Allows for customization of the folder pane. Accounts can be rearranged and the startup folder can be chosen.
Show contact photo and other info from Local Dir, Addressbook, LDAP, Facebook, LinkedIn, Flickr, Gravatar etc
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.
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...
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.
Adds icons to buttons and/or menus.
Reinstates the extensions.checkCompatibility preference without respect to the current application version.