Is this a question about Thunderbird?

If that is the case then we can move the question over to Thunderbird support.

Yes, I posted to the wrong forum.

Thanks. Moving thread over to Thunderbird sutport.

What are you trying to achieve in the first place?

Files are not retaining all messages. Messages are being deleted after a short period of time. I need to retain sent and deleted messages for a longer period. Thanks

Messages are being deleted after a short period of time.

By whom?

What is your account type - POP or IMAP?

IMAP. The emails are usually saved in Thunderbird, not on the mail server, but since the last update the files must be smaller because it is losing mail once the file gets full. I used to be able to have a years worth in the sent and deleted files but now it is about a month and a half. Thanks

The emails are usually saved in Thunderbird, not on the mail server,

With IMAP messages are stored on the server. That's the whole point of using IMAP. If all your messages are on your local disk, you'd have to deliberately move them off of the server to your Local Folders account. But if you were doing that you probably wouldn't have a space problem.

Check with your email provider about your quota on the server.

Also see http://kb.mozillazine.org/Disappearing_mail