How to Get Mozilla Thunderbird to Delete Messages on the Mail Server When Using IMAP

When using Mozilla Thunderbird to access your email account using IMAP, you may find that whenever you delete messages in Thunderbird, those messages aren’t really deleted on the server.

For instance, when you check the same email account using Webmail, you might find that those messages appear to be marked for deletion, rather than being actually deleted as you might expect.

To get Mozilla Thunderbird to delete messages from the mail server when you delete them in Thunderbird when using IMAP, perform the following steps:

  1. In Thunderbird, right-click your email account in the left sidebar, then select Settings.

  2. Click Server Settings.

  3. Under the Server Settings heading, for the option labeled When I delete a message, select Move it to this folder:, then from the dropdown menu, select Inbox > Trash.

  4. Click OK to save your changes.

  5. While still in Thunderbird, look for a menu named Options. Click that, then go to Options > Advanced > General.

  6. Under the Advanced Configuration heading, click the Config Editor... button.

  7. Set the value of mail.imap.expunge_after_delete to true.

  8. The above steps affect only messages that are deleted at any point after you’ve completed those steps.

    For messages that were deleted in Thunderbird prior to performing the above steps, and that are currently still marked for deletion on the server, you can delete them from the mail server by selecting the desired account in Thunderbird, then selecting File > Compact Folders.

Now whenever you delete messages using Mozilla Thunderbird, it should also move them to the Trash folder on the mail server accordingly, and when you delete those messages from the Trash folder, it should remove them from the mail server as well.