We are experiencing recurring issues with email in terms of rate limiting and the speed at which emails are sent.
One of the ways email systems automatically detect spam is the rate at which email is delivered. With large organizations like GNENC normal mail can be fast enough to be "thought" of as spam.
We are working to rate limit our outgoing mail so that we do not trigger these temporary spam labels. In the interim it may take longer than normal for your mail to be delivered.
Thanks for your understanding and patience.