All of my emails are showing ***UNCHECKED*** in the subject line. What is the problem and how do I fix it?

This means that your ClamAV anti-virus service in Zimbra has stopped working. You will need to start it:

Log into your Unix shell as user Zimbra and type the following commands:

cd \opt\zimbra\bin\./zmclamdctl start (press enter)

./zmantivirusctl start (press enter)

Check to make sure it is running:

./zmcontrol status