The “Date” column in the Thunderbird / SeaMonkey thread pane shows the date from the header of the email message, which is not necessarily an accurate indication of when you received it. The “Received” column is supposed to show when the message arrived in your mailbox, but it does not work properly for IMAP folders. It will if you install this add-on!
- This will take effect for newly received messages as soon as you restart Thunderbird or SeaMonkey. If you want to fix the “Received“ column values for messages that were already in a folder when you installed the add-on, then you must open the folder's properties dialog (right-click or ctrl-click on it and select “Properties...”) and click the “Repair Folder” button. Note that this will, unfortunately, reset your visible columns and their widths, so if you've made changes to the default thread pane layout for the folder, you will have to redo them afte repairing it.
- Even if you sort by “Received”, threads will still sort by “Date”. This is due to a bug in the core Thunderbird code which can't be fixed in an add-on.