> The size of the inbox is 4.5.

GB? MB?

> Is there a limit on the inbox size?

No

See https://support.mozilla.org/en-US/kb/cannot-receive-messages. What works?

Hi Wayne, Yes the inbox Suze us 4.5Gb. It has 47,101 messages in it.

That's a bit risky :) You are saying you have all of those emails stored in just one single mbox text file.

Maybe the mbox file has got corrupted - as a precaution I would suggest you do the following: I would advise that you create some folders to help organise emails eg: Business, Family, Friends, Club, Bills, etc Then move all the emails out of Inbox into relevant folders.

Finally try to compact the Inbox to clean it up.

You say Thundrebird is not receiving new mail... If you logon to webmail account via a browser, are there new not downloaded emails in the server Inbox ? If no then server is not receiving new mail, so you cannot download new mail. Maybe you have used up all your server quota. If this is a gmail account and you use POP in Thunderbird - then gmail can get awkward and curtail any downloads until you remove a load of old mail off the server. As POP accounts cannot put deleted messages into the server Trash - you may discover a load of emails in the 'All Mail' folder which do not have 'labels' - emails got archived. Delete those old emails to release space on server. Note: If you use an IMAP account in Thunderbird, then it would be wise to get copies of important old emails in your Imap acount into a folder in your 'Local Folder' account before deleting anything off the server.

What server are you using ? eg: gmail Are you using a Pop or Imap mail account ? If pop do you have the setting to 'Leave messages on server' ?