Subaddress Reply

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

An example:

1. You primary mail address is tim@mymail.tld
2. You receive a mail to the subaddress tim+mailinglists@mymail.tld
3. When you reply to this mail the sender is set to tim+mailinglists@mymail.tld by this Add-on

What is a subaddress?

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 tim@mymail.tld you will also receive mails that are send to tim+mailinglists@mymail.tld or tim+shopping@mymail.tld.

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. tim+a-company@mymail.tld

Permissions

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

tabs

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.

compose

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.

messagesRead

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.