Message Composition

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Send Later

True "Send Later" functionality to schedule the time for sending an email.

Rated 5 out of 5 stars (250)
91,444 users

Mail Merge

Create and Save or Send Multiple Individual and Personalized Messages from a Draft

Rated 5 out of 5 stars (201)
71,874 users

Signature Switch

Switch the signature on/off or choose a new one from your predefined set.

Rated 4 out of 5 stars (265)
54,498 users

FileLink Provider for Dropbox

Uploads your large attachments to your Dropbox instead of sending them by email. This uses Thunderbird's FileLink feature.

Rated 4 out of 5 stars (14)
43,760 users

Owl for Exchange

Allows you to use your Exchange and Office365 email account with Thunderbird using Outlook Web Access (OWA).

Rated 5 out of 5 stars (110)
42,561 users

Emoji

Add emojis to your e-mails.

Rated 4 out of 5 stars (45)
24,552 users

*cloud - FileLink for Nextcloud and ownCloud Featured

Upload large attachments to your Cloud and send the link by email

Rated 5 out of 5 stars (36)
24,477 users

Check and Send

Check the message contents and addresses before you send the message...

Rated 4 out of 5 stars (43)
20,788 users

Grammar and Spell Checker — LanguageTool

Check your emails for spelling and grammar issues

Rated 4 out of 5 stars (18)
19,916 users

ThunderHTMLedit

Thunderbird HTML editor. This add-on adds a HTML tab to the composition window where you can see and edit the HTML source of the message.

Rated 5 out of 5 stars (29)
19,525 users

FileLink provider for Send

Securely encrypt and upload large attachments to any Send service instance (formerly Firefox Send).

Rated 5 out of 5 stars (4)
16,616 users

FileLink Provider for Box

Uploads your large attachments to your Box instead of sending them by email.

Rated 4 out of 5 stars (4)
16,348 users

Flex Confirm Mail

Confirm mail address and attachments based on flexible rules.

Rated 4 out of 5 stars (10)
14,183 users

Shrunked Image Resizer

Make your photos smaller, so they don't take forever to email.

Rated 4 out of 5 stars (80)
13,610 users

ReplyWithHeader

Outlook style headers and few goodies for Thunderbird.

Rated 5 out of 5 stars (59)
10,301 users

CategoryManager

Category manager for Thunderbird contacts, also allows to send an email to all members of a category (categories can be used as contact groups).

Rated 5 out of 5 stars (15)
8,926 users

Textmarker

Highlights selected text when composing emails. Default colour is yellow - other colours are available via Options.
(Works only during writing an e-mail, i.e. only in the compose window.)

Rated 5 out of 5 stars (24)
8,735 users

Simple Mail Redirection

Allows you to resend (also known as redirect) email messages.
Uses 'cardbook' if installed

Bases on the add-on 'Mail Redirect' by Onno Ekker and Pawel Krzesniak

Please see the support page on how to use and why it sometimes does not work!

Rated 5 out of 5 stars (23)
8,018 users

Identity Chooser

Identity Chooser helps you to always use the correct identity when composing a new email.

Rated 4 out of 5 stars (136)
7,537 users

BorderColors D

Shows a colorful border around the "New Message" window, so you can tell different identities apart.

Builds on the original BorderColors and the "GT" version, adding different border styles.

Rated 4 out of 5 stars (25)
6,892 users