Mozilla Thunder can't get mail

It seems like I have seen this before in past. But I can not remeber what the cure was. When programs goes to get mail , comes back with error message.
Unable to write the email to mailbox. Make the file system allows you the write privileges, and you have enough disk space to copy mailbox. I did yesterday something I thought that was not right. Most ot the mail, no matter who sender was it was same mail from a mate matching site. I forgot which one. Now this. I have ran AVG virus program and it seems to find something but can not do any thing about it. Got any clues as to what I have here?
Thanks

 

rksnc,

This is the error, also how to troubleshoot, and fix:

Mail Error - Unable to write mail to the mailbox. Make sure the system allows you write privileges, and you have enough space to copy the mailbox.

If you continue to have problems after trying the above suggestions, please let us know.