Have about 300 users on a system being used as a mail server.  Have one user who is getting a quota full error.  Looked into his folders and there are no messages at all, but quotas still say he has 20MB (quota limit).  I have disabled and re-enabled quotas with no luck in fixing the problem.  I have turned off his quota till I fix the problem.
Any ideas where to look to see what is happening?
TIA