True "Send Later" functionality to schedule the time for sending an email.
Create and Save or Send Multiple Individual and Personalized Messages from a Draft
Check your emails for spelling and grammar issues
Uploads your large attachments to your Dropbox instead of sending them by email. This uses Thunderbird's FileLink feature.
Allows you to use your Exchange and Office365 email account with Thunderbird using Outlook Web Access (OWA).
Switch the signature on/off or choose a new one from your predefined set.
Securely encrypt and upload large attachments to any Send service instance (formerly Firefox Send).
Upload large attachments to your Cloud and send the link by email
Add emojis to your e-mails.
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.)
Check the message contents and addresses before you send the message...
Confirm mail address and attachments based on flexible rules.
(This project was renamed from "Flex Confirm Mail" to "FlexConfirmMail", due to a branding reason.)
Uploads your large attachments to your Box instead of sending them by email.
Make your photos smaller, so they don't take forever to email.
*Shrunked Image Resizer is no longer maintained.*
Outlook style headers and few goodies for Thunderbird.
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!
Category manager for Thunderbird contacts, also allows to send an email to all members of a category (categories can be used as contact groups).
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.
Create file attachments directly from the system clipboard.
Identity Chooser helps you to always use the correct identity when composing a new email.