Add-ons

ThunderBirthDay by ingomueller.net

Display birthdays from the Thunderbird addressbooks as events in Lightning.

Mail Summaries by squib

Adds a summary of mail accounts and folders to replace the account central pane and the empty folder preview

Zindus by Leni Mayo

Google and Zimbra contact sync for Thunderbird. (TB 24 and above NOT supported)

Extra Folder Columns by Joey Minta, Thunderbird Development Team

This extension is for those TB3 users who want the multiple-columns view that TB2 allowed

IMPORTANT: If you are using Thunderbird 38 or later, uninstall this addon. The functionality is in core now.

Return Receipt Toolbar Button by Leszek Życzkowski

Allow you to add a Return Receipt button to mail compose window toolbar.

Birthday Reminder by Sebastian Apel

Birthday Reminder reminds of upcoming birthdays for all contacts in Thunderbird's address book. Supports Lightning, reminders and even Google Calendar :-)

Lightning Nightly Updater (Unofficial) by Oliver S.

Quickly get to the latest nightly build of Lightning relevant to the version of Thunderbird and the OS you're on.

BorderColors by Mike Krieger

Color-codes compose windows depending the active e-mail identity, to avoid sending messages from the wrong account.

Collector's Note Handy add-on when using several mail accounts, to avoid you send an email from the wrong account. It's a pity it stopped working 'til TB 6 I think and haven't been updated again.

SyncMab by Jan Pavek

This extensions can import and export mozilla address books at startup and exit of Thunderbird. You can first save a mab at a specific location e.g. on a network or the internet (Version 2.0) and then let it be updated every time TB starts up or...

notto by andreifa

Do not send mail to the addresses found into notTo field.

The Witcher 3 Ciri by xRainx