Extensions by Name

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UMTools Requires Restart

Add new options to TB's Unsent Messages behavior.. ...

Rated 3 out of 5 stars (3)
0 users

Un-Safelinks Requires Restart

Replace URLs which have been rewritten by Office 365 Advanced Threat Protection with the original URL.

Not yet rated
2 users

Undigestify Requires Restart

Undigestify RFC 1153, ListStar, and Yahoo digest messages

Not yet rated
1 user

Ungender

Eine Thunderbird-Erweiterung, welches Binnen-Is und Ähnliches von Webseiten entfernt. Es basiert auf der bekannten Firefox Erweiterung Binnen-I be gone.

Rated 4 out of 5 stars (5)
221 users

Unicodify – Text transformer

Easily and quickly autocorrect common symbols as ¼, transform text to “Unicode fonts” and change the casing.

Rated 5 out of 5 stars (1)
324 users

Unified Folders Debugging

An add-on to help debugging problems with the Unified Folders mode.

Rated 4 out of 5 stars (8)
253 users

Unified Search Requires Restart

Unify the global search box and the quick filter box in a new widget (the 'Unified Search Widget') with all filter and search capabilities at once.

Rated 4 out of 5 stars (28)
18 users

Unifinder Views Requires Restart

Add more views to the unifinder (event list) in Sunbird and Lightning.

Rated 5 out of 5 stars (1)
0 users

UnInbox - Quick Access

Quick Access to UnInbox in a new tab with just one click on a simple, stylish icon button on your Spaces toolbar.

Not yet rated
1 user

Unmangle Microsoft ATP Safelinks

Users of outlook.com and o365 who have Advanced Thread Protection enabled will have all URL's in emails changed to redirect them to an Microsoft filter before opening. This is a bad idea.

This plugin will change the URL back to the original value.

Rated 5 out of 5 stars (6)
767 users

UnMHT

UnMHT allows you to view MHT (MHTML) web archive format files, and save complete web pages, including text and graphics, into a single MHT file in Firefox/SeaMonkey.

Rated 4 out of 5 stars (300)
41 users

Unread Count Requires Restart

Maintains a file in the profile root directory with counts for unread messages per account. Useful for display in generic status bar, e.g.: taffybar, xmobar, dzen2, etc

Rated 5 out of 5 stars (2)
1 user

Unselect Message Requires Restart

Prevents Thunderbird from selecting the next message after you've deleted or moved the previously selected ones. Stay in control of which message you want to have selected and displayed in the preview pane; that piece of spam you're deleting...

Rated 4 out of 5 stars (29)
0 users

Unsubscribe

Lightweight solution to simplify unsubscribing from newsletters

Rated 3 out of 5 stars (12)
1,212 users

Update Notifier Requires Restart

Note from Mozilla: This add-on has been discontinued. Try Add-on Update Checker instead.

Notifies you when updates are available for your extensions and themes.

Rated 5 out of 5 stars (162)
0 users

update-test

DO NOT install, this is for testing the update mechanism.

If you are interested in the functionality, use quicker quicksearch instead

Rated 3 out of 5 stars (1)
3 users

UrgentMail

Raise X11 urgent flag if new mail is received.

This addon listens for incoming mails and causes the Thunderbird window to draw attention.

Rated 5 out of 5 stars (3)
257 users

URL Link

URL Link is a small Thunderbird extension that allows you to select a non-URL in a mail/news message or web-page, and open it in a browser window.

Rated 4 out of 5 stars (6)
2,208 users

URLFilter

Block advertisement and access to adult sites

Rated 4 out of 5 stars (23)
21 users

Use Bcc Instead Requires Restart

Sorry but this addon is no longer supported in TB 60. See below.
Who among us has not made the mistake of sending a 'broadcast' email to a large number of recipients without using BCC; thereby revealing everyone's email addresses to all?

Rated 5 out of 5 stars (31)
65 users