Hello, It seems you hit a quota limitation on your mail server. There are 2 scenarios: - Ask your mail provider for a bigger quota - Delete some messages (usually people forget to delete tons of messages in Sent folder)

Good luck!

Thank you for your advice, I am most grateful. However, I'm unable to delete sent or deleted messages. I get a pop up message to say the operation exceeds capacity. Any further advice?

Use your online account to do that. If that fails, contact your email provider for assistance.

When you use up all the quota/space that is allowed, that account can no longer receive emails nor send emails because there is no space on server.

You will need to delete a lot of emails via your webmail account. If you have some emails that are really very important then get a 'copy' of that email and put it into 'Local Folders' mail account because if you delete those emails off server to create a lot of space then they will get deleted from an imap account. Use the 'Local Folders' mail account folders to store copies of important emails then those copies will be stored on your computer as independent copies.

Exit Thunderbird.

Logon to your webmail account via a browser. You need to delete alot of old emails which you really do not need to keep. Also make sure the server Spam folder is emptied. Then empty the 'Trash'.

I'm assuming you have an imap mail account in Thunderbird. When you next restart Thunderbird, those imap folders should synchronise with the server folders and display whatever is left on the server. Remember whatever you delete off the server will also get deleted out of the imap account, so do not be surprised to see less emails.