SBS 2003 running Exchange 2003. All users worked correctly as of 4 days ago. One user reported yesterday that he had not received any email all day. Confirmed that he could send internally and externally but could not receive either.
I sent a test email from a web email account and received an error referring to a size quota. I increased his quota (though he was not using much space at all). Problem persists.
I compared his account to that of a known working account and found them to be identical.