I have an Exchange 2013 server having issues delivering emails to Gmail addresses (and/or googleapps hosted email). I'm receiving Delivery Delayed error when I check mail queue.
Error: 400 4.4.7
If I do a telnet test to the domain, it comes back OK, but emails are still delayed.
The IP address is not listed on any blacklists.
rDNS is ok.
Not sure what else to check... Any help would be appreciative.