Recently Updated Extensions
Makes every page to have light text on dark background (exact colors are customizable)
Firefox version is here: https://addons.mozilla.org/firefox/addon/dark-background-light-text/
Mouse Gestures Suite Requires Restart
Mouse gestures for SeaMonkey & Firefox: navigate & execute commands using mouse gestures (with single mouse button) and rocker gestures (by pressing 2 mouse buttons). Also: scroll wheel navigation, page scrolling, tab scrolling.
Be in control of which cross-site requests are allowed. Improve the privacy of your browsing by not letting other sites know your browsing habits. Secure yourself from Cross-Site Request Forgery (CSRF) and other attacks.
CipherFox Requires Restart
Displays the current SSL/TLS cipher, protocol and certificate chain in the Add-on bar and Site ID dialog
Save Images Requires Restart
Save Images saves the images from the current tab page, from the cache, to a specified location, with either the images original file name or a file name that you specify.
Password Tags Requires Restart
Adds metadata and sortable tags to the password manager.
ToggleReplied Requires Restart
Enables toggling of replied, forwarded, and redirected states of messages.
Multi Web Search Requires Restart
For those who are looking for and want to find!
Find the most relevant information from the Web with a single request to different search engines and get the results on a single page
Enigmail Requires Restart Featured
OpenPGP message encryption and authentication for Thunderbird and SeaMonkey.
Auto delete cookies, localStorage and IndexedDB objects as soon as they become unused
PrefBar Requires Restart
DOM Inspector Plus! [dm] Requires Restart
Improved DOM Inspector! [dm version]. Box Model new layout & more data, see screenshot!. Horizontal scroll for Dom-Tree, and some more.
Inspects the structure and properties of a window and its contents.
Send Later Requires Restart
True "Send Later" functionality to schedule the time for sending an email.
Show InOut Requires Restart
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...
Copy Sent to Current Requires Restart
Allows to place a copy of sent messages (aka FCC) into the currently active folder or any other folder you choose, when you create the message. Usually the copies are placed into the 'Sent' folder. For replies, you may also move the original message.
'Classic Toolbar Buttons' add-on restores old toolbar button ui (known from Fx 4-7s small view, Fx 4-12s large view & Tb 5-14) for current Firefox, Thunderbird and Seamonkey versions.
Beta builds on versions page!
Decide whether to allow or block remote content in messages by comparing the names of the folders in which they are located to configured regular expressions.
Add-on for Thunderbird that replaces the built-in notifications with OS native ones. It supports most Linux Desktop Environments as well as Windows 8.1/10.
Thunderbird Integration for JIRA Requires Restart
This is a plugin for Thunderbird 3.3+ which is able to create Atlassian Jira issues out of e-mails or add the content of an e-mail as a comment on an Jira issue.
Shrunked Image Resizer Requires Restart
Make your photos smaller, so they don't take forever to email or send to websites.
This extension is not being converted to a WebExtension.