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
Quicktext is an extension for Thunderbird that lets you create templates that can be easily inserted into your own emails.
Polish spell-check dictionary for Firefox 2.0/3.0pre, Thunderbird 2.0/3.0a1 and SeaMonkey 1.1/2.0a1...
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!
Search and remove messages which are the same as other messages in your mail folders (referred to as duplicates or dupes).
British English Dictionary R1.19 for Firefox, Thunderbird and SeaMonkey by David Bartlett.
To enable, right-click in a multi-line text box, select "Languages", then "English / United Kingdom".
SmartTemplate4 offers an easy way to automatically create customized replies by auto-inserting various mail headers. Templates can be created for every account as well as for the default (all email accounts). Also supports the Stationery Add-on.
Persistent sticky notes for Thunderbird associated to mails.
This is a port to Thunderbird >= 3 and Seamonkey >= 2 based on XNote 2.1.0 ( https://addons.mozilla.org/en-US/thunderbird/addon/3093 ) with bugfixes and additional features.
Displays icon for user agent of received mails.
This add-on provides a follow-up email feature for Thunderbird.