Organize your schedule and life's important events in a calendar that's fully integrated with your Thunderbird email. Manage multiple calendars, create your daily to do list, invite friends to events, and subscribe to public calendars.
Allows bidirectional access to Google Calendar
OpenPGP message encryption and authentication for Thunderbird and SeaMonkey.
Access to Google contacts and synchronize them with Thunderbird address books.
Switch the signature on/off or choose a new one from your predefined set...
Adds toolbar buttons to the customize toolbar window in several programs including Firefox, Thunderbird and SeaMonkey. Some of the buttons make commonly preformed actions quicker, others add new functionality.
Quicktext is an extension for Thunderbird that lets you create templates that can be easily inserted into your own emails.
Did your friend send you a cool link? Want to read the rest of that interesting article? Don't want to open up your web browser just to view it? You don't have to! Just view it in Thunderbird with ThunderBrowse!
Allow to redirect (a.k.a. "bounce") mail messages to other recipients.
Search and remove messages which are the same as other messages in your mail folders (referred to as duplicates or dupes).
Extracts all attachments from selected messages and then can delete, detach or mark-read.
Thunderbird Message Filter Import/Export is a thunderbird/mozilla extension to import/export message filters.
Powerful message searching through expressions. Type "from:fred to:tom" to see all messages from Fred to Tom in the current view. Support 'regular expressions' and 'click to search'.