This is on Exchange 2007 can't find the forum.
Today i received that someone outside of the domain was trying to email in and that the server is responding with an error Reason: Remote host said: 554 5.1.0 Sender denied
We removed the entry for the domain that was in the Anti-Spam, Sender Filtering, Blocked Senders. Then had them try to send again and same error.
The status for "Sender Filtering" is "Enabled". I entered a personal email address in the blocked senders list and it doesn't block it at all.
Any help would be appreciated.