Hi GHuey41,
First, I would like to collect some detailed information about the issue.
1. Is your Office 365 tenant after the service upgrade? To check it, please refer to the following article.
http://office.microsoft.com/en-us/am-i-using-office-365-after-the-service-upgrade-HA103982331.aspx
2. Do you have a Hybrid deployment?
3. Does Forefront mean Forefront Online Protection for Exchange (FOPE)?
As for the first question, based on my experience, the spam issue should have no direct link with the symptom mentioned. Adding users to FOPE is for other special configurations at FOPE side.
As for the second question, if an email is delivered to Office 365, we can track that message after several minutes.
To troubleshoot the SPAM issue, please provide the entire NDR received.
Thanks,
Claud