email add-on not attaching emails to contacts

email add-on not attaching emails to contacts

I have added the mail add-on to ZCRM.  The problem I am experiencing is that it attaches the email history to the contact records only on SENT mail.  I can not figure out why RECEIVED mail for contacts are not being recorded.

Is this normal?  It seems as if it did both for awhile, because some contacts have records of both happening.  I have tested this multiple times since and NO received emails get attached now.

Thanks for your help.
Brad