We operate a shared e-mail address in our small office where multiple machines access the same Inbox via IMAP, using Thunderbird clients configured identically. An unusual scenario perhaps, but this is only a small office and it has worked for years. Also allows access to the Inbox when away from the office via our mail host`s webmail facility (Strato-hosting.co.uk). If it`s not a general enquiry that anyone can answer, in order to keep track of what new mail is for who, the coloured tags have been customised so the different colour refers to a different person, rather than the default Later / To Do / etc. We leave the message marked unread, press 1 - 6 to tag it for whoever, and they can then filter for messages tagged for them when they get in. Again, an unusual scenario perhaps, but it has also worked too....until now. Lately, as in the last week or so, the existing tags of all the messages that have already been tagged have cleared, and not deliberately. Also if we try to tag anything now, it won`t "stick". There is also an error message coming back from the server whenever anything is marked or unmarked as spam. In order to keep things under control, all the individual clients are configured never to move spam - automatic filtering and moving of spam is done only by the Thunderbird instance that is left running all the time on our server. However now and then the individual machines decide to mark something as spam, even if it remains in the Inbox. (OT but I wish there were a way to completely disable junk/spam controls in Thunderbird, perhaps there is now?). Since this problem with the tags has happened, an error message is returned any time the little spam flame icon is clicked to set or clear it, and although it doesn`t appear when trying to tag messages, I wonder if it is related to that problem too. "Thunderbird - The current operation on Inbox did not succeed. The mail server for account [i]our@email.account[/i] responded: [LIMIT] STORE failed". Interestingly, this does not occur on any of the other mailboxes (as well as Sent, etc, there are a couple of others for specific subjects), only the main Inbox. There are presently 2239 messages in the Inbox, but this does not appear to have reached any storage limits, we get an indication on the status bar if it gets to >75% full which is not presently there. Everything else works regarding marking read/unread, moving, copying, sending, receiving. Nobody has changed anything that anyone is aware of. The individual clients are set up to automatically update and the one on this machine just now is 38.2.0, not sure when the last update was or whether that corresponded to this problem. Have spoken to the tech support for our mail host and they can`t see anything wrong with the Inbox, and did not seem to recognise that error message either. Suggesting I try Mozilla / Thunderbird support, here I am. So, what are the haps? Anyone know what that error means, and how it might be fixed? I realise our usage might be unusual, but it has worked very well until now. Any assistance is gratefully received. Sorry this is such an extensive message. It would have taken me too long to write a shorter one.