RSS, News and Blogging
Copy Pure Text Requires Restart
Allows to copy selected text as plain text by adding a 'Copy as Text' menu item to context menu.
infoRSS Requires Restart
Displays RSS, Atom, Twitter, parsed HTML and NNTP feed in a scrolling area in the status bar. Compatible with podcasting RSS which can be downloaded directly. It's also a good Google email notifier.
Display Mail User Agent Requires Restart
Displays icon for user agent of received mails.
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.