Well I did a test and according to the documentation and if I understand correctly we should input an e-mail address somewhere but the field doesn't seems to exists.
Also I've set the reminder 1 hour before the event occurs but had no notification neither for the event creator nor the attendees.
Also one of the attendee is external to the domain (a mail account on another server which is checked with IMAP in emClent). I've received the event creation notification on the externeal account and accepted it.
But the status of the attendee remains unknown in the event.
However the inbox of the event creator received the invitation acceptance from the external account, but displays it as a "You've been invited" not as an Accepted invitation...
Not sure here if it's a emClient or SM issue.
Ron you had some success with the reminders working and invitations acceptance from external attendees ? (in case you tested it)