Alert for unread email(s)

Would be nice for owners to have a way to discover when a guest has not read certain emails.

Options would be
- report/list sent to owners daily
- add as a trigger that owners could use to email themselves
- make visible from the Ribbon (my favorite!) along with other alerts such as "unsigned rental agreements" and "not fully paid".

Maybe add a checkbox to email templates so that only certain emails can be flagged as *must read*.

I just checked my email history report filtered down to my most important "thanks for booking" and "arrival day info" emails and in both cases about 10-20% have never been read. Probably these are my problem guests who show up unprepared !