'Has been read by', is this possible?

No programming information at this time, just a concept question. (OK,  perhaps just a little
more information than Yes or No.  :-)

We have a mailbox which is monitored by N people.
Is it possible, automation via VBA is ok (unless it's a month project), to set it up
so if the mail is opened, not just touched/previewed, but opened full screen, the reader
of the mail is recorded and can be noted by all other users of the mailbox?
We don't want more email saying it's been read.  It should be an attribute, now,
of the mail itself.

So, you'd come across letter A, view it in the preview window (not full screen)
and see that John had already read this (read this full screen).

This is not setting flags.  We want to see names.  Maybe this functionality is already there.

Thanks