550 Access denied (not in relay or upstream list)

Question

I am unable to receive emails going through my mail server. 
 
 I get an immediate bounce back with this error 
 
 The error that the other server returned was:
550 Access denied (not in relay or upstream list) 
 If i disable SMTP protection all together the mail flows fine. I cant seem to find the problem in the smtp settings. I've had the SMTP protection on for quite some time now without issue. I recently updated to 9.353-4 and then this started to happen.

jflex · Accepted Answer

I already had the mail server in the upstream and relay lists. 
 
I did find the problem. I looked at one of my other UTMs and noticed that the one with the issue had the transparent mode enabled under advanced. 
 
After removing that, everything started working again.