I have recently been getting the following error message in Mail - "The IMAP command 'UID copy' (to Deleted messages) failed for the mailbox INBOX with server error: You exceeded your mail quota". This means little to me! I temporarily overcome the problem by emptying the Trash mailbox for the particular email account but the deleted items all re-appear next time I log on and again I get the same message. I'm running OS 10.11.2 and Mail 9.2. The mailbox behaviours under Preferences for this account, are set to delete messages to Trash mailbox and store deleted messages on server, also permanently delete messages after 1 month. Any ideas?
I suspect this is your email provider (Waitrose?) complaining that your email exceeds the allowed space and also their IMAP service not working as well as it should and not obeying Mail's instructions.
Copy email you want to keep to a mailbox "on my Mac" and then log on to their webmail service and delete unwanted email there.
Thanks Mick, when i went into webmail I could see that I had used up all my 100MB allowance with over 700 emails still in my inbox. I guess the Waitrose server is not deleting the messages as it should do, after one month. Anyway problem is now sorted so again thanks for your usual apposite advice!
David Fleetwood 