LAB: Exchange 2013 , Mail Stuck in Queue, DNS Set wrong in ECP

1st October was Release date Exchange 2016. So we finally take a look at Exchange 2013 in our Labs ;-) Exchange 2016 seems nothing else then Exchange 2013 SP2. Most of the Office365 things are now also available on Premise (On inhouse Exchange 2013).

First bug we had in Exchange 2013 with Outlook 2010.

Error 4.4.1 Mail does not get delivered to 2013 Test mailbox after Update to CU10.

You see E-Mail incoming in Exchange 2013 from 2007/2010 or itself BUT not delivered to Mailboxes.

Becaue of the Outlook Anywhere Proxy the internal and External DNS are important. There are also several Hotfixes

related in that Direction for Outlook 2010 and 2013. Mostly cumulative Hotfixes after SP2.

https://support.microsoft.com/en-us/kb/2839517

For Outlook 2010.

Get an Error 4.4.1 in Exchange 2013 GUI Toolbox.

1. Check DNS Settings under ECP / Server / DNS-Lookups
2. Check that the Services that work with that are running

The issue was related to having an external DNS server entered in the properties of the servers NIC. I had the internal primary and secondary DNS servers entered in the NIC, and in the advanced porperties I entered the IP address of our ISP's DNS server. I have done this for that past 8 years in my server NIC configurations and it has saved my butt numerous times. It allows the server to still access the Internet if one\both of the internal DNS servers goes offline\has issues, or if there are network issues. Until now I have never had an issue with this configuration.  I do not know if it is an Exchange 2013 or a server 2012 thing or what, but either way we removed the external DNS server from the NIC and the issue has not returned.

http://www.experts-exchange.com/Software/Server_Software/Email_Servers/Exchange/Q_28220238.html