We use app river to filter out any spam/viruses prior to coming to our Exchange 2013 server. We are experiencing that some emails are being delayed for 1800 seconds through out the day, a sort of blacklisting by our Exchange server. Does 1800 seconds or 30 mins ring a bell for anyone, I'm not sure what setting is causing this. During the blacklist other emails are able to flow without issue. These messages just seem to be stuck for 30 mins and then get resent and go thru after that timeout period.
We are also running Symantec Mail Security 7.5 on that ex server. We have the Antivirus turned on and do not have any spam settings enabled.
This is the message that app river is showing in their logs:
rsp: 451 4.7.0 Temporary server error. Please try again later. PRX5
message body rejected, got:451 4.7.0 Temporary server error. Please try again later. PRX5
batch delayed for 1800 seconds
I've searched 451 4.7.0 Temporary server error. Please try again later. PRX5, created host files, manually applied dns entries to the server dns lookups setting and changed the default front end receive connector scoping from any avil ip addy to a specific static ip, but no luck.