I can't find any information about this specific problem elsewhere. I use IMAP to access my email account from multiple devices: laptop, destop, and android phone. I use Thunderbird on my computers but the built-in email client on my phone. All messages that I send end up in the "Sent" folder for that account (on the account's server), regardless of which device I send them from (I've doublechecked this). However messages are only marked as replied to, forwarded, etc. on the computer that I actually sent them from. An example: I reply to email 1 from my laptop. Status of this email is shown as replied to on the laptop but not on the desktop. I reply to email 2 from my desktop. Status of this email is shown as replied to on the desktop but not on the laptop. (The same is true for messages I send from my phone, but since I don't use Thunderbird on my phone this obvious isn't the forum for that.) An additional twist is that the laptop and desktop are both new (and running Windows 8.1, if that makes any difference), but if I fire up my old laptop (Windows 7), then messages replied to from the new desktop computer are shown as replied to on the old laptop, but not the new laptop. So for the examples above: I reply to email 1 from my new laptop. Status of this email is shown as replied to on the new laptop but not on the desktop or the old laptop. I reply to email 2 from my desktop. Status of this email is shown as replied to on the desktop and the old laptop, but not on the new laptop. The main reason why I think this is strange is because I know that the replies are all ending up on the server as they should, meaning that there's always a sort of record of the message being sent, regardless of where it is sent from. How can I sync the message status so that it shows up on all my devices? It seems like it should be possible, because how else could the old laptop manage to sync the status with the new desktop? As far as I can tell I have all the same settings on all devices.