I had another problem today,
I tried to forward a newsletter to a colleague in 2 email addresses,
the one was an exchange one and the other a yahoo address,
the email wasn't delivered in any of the two,
I finally managed to succeed when I sent it over to his hotmail!!!
Of course, the problem is that I wasn't notified in any case (neither did he,
he just didn't receive any email),
which is a shame for gmail and possible its reputation?