When I send out invites too a Webinar, I add all attendees as BCC recipients.

However some of my attendees say they can see a list of all people
invited/accepted when they look at the invitation in their calendar.

Also when some people send their reply (accept/tentative/decline) the reply
is received by the organisor(which is right) and also,sometimes, by a random
person (who was part of the attendee/BCC list)

Has any1 else come across this?

How can I avoid this from happening?

I should also add that it only happens to the odd person, (1out of every 100)

Thanks