Set Thunderbird to auto expunge deleted emails off server here: "Tools → Account Settings → Server Settings for the IMAP mail account Select: Clean up (“Expunge”) Inbox on Exit it will compact the Inbox folder when you exit Thunderbird.
Set Thunderbird to auto expunge deleted emails off server here: "Tools → Account Settings → Server Settings for the IMAP mail account Select: Clean up (“Expunge”) Inbox on Exit it will compact the Inbox folder when you exit Thunderbird.