This Thunderbird Add-on handles replying to a messages that were sent to a subaddess.

An example:

1. You primary mail address is [email protected]
2. You receive a mail to the subaddress [email protected]
3. When you reply to this mail the sender is set to [email protected] by this Add-on

Mail software like Postfix or qmail or providers like Gmail allow the usage of so called subaddresses.

This means you can add suffixes to your primary mail address and get an unlimited amount of mail addresses.

Postfix or Gmail use + as a separator by default, qmail uses -.

This means when your primary address is [email protected] you will also receive mails that are send to [email protected] or [email protected].

This allows you to filter emails depending on the recipient to which they are sent. I also allows you to track if a company is giving your email address to third parties when you embed the company's name in your mail address e.g. [email protected]

These permissions are required by the Add-on for these reasons:

Watch for new tabs of type messageCompose with an event listener to browser.tabs.onCreated. We need the tab.id to fetch the Compose details.

We fetch the Compose details to check if the created message is a reply to a message sent to a subaddress.

If it is a reply we set the From-Address to the subaddress if required.

We fetch the message that the user replies to. The message is needed to get its recipients to check if it was sent to a subaddress.