Are you sure there is no "Subscribe" option in the context menu? You have to right-click on the account name, not the folder itself. And are you sure they are IMAP folders? There will be no Subscribe option for a POP3 account. I did a short test just now: - I added a new folder in Roundcube and copied a few messages into it. Then I looked at the Subscribe list and was surprised and pleased that the new folder showed up there and was automatically subscribed. However, the folder did not show up in the Folders pane until I collapsed and expanded the folders list. Re-starting Thunderbird does it, too. - I renamed that folder in Roundcube. The folder acted similarly in Thunderbird as above - it was immediately visible with the new name in the Subscribe menu, but I had to do the collapse/expand thing to make it show up in the Folders list. How does my experience compare with yours? I notice that there are "Subscribe" buttons in Roundcube that accomplish the same thing as the Subscribe check boxes in Thunderbird. Maybe it would help to unsubscribe from all folders, then re-subscribe, perhaps restarting Thunderbird in between.