This a small, simple environment. There is a MS Server 2012 R2 server hypervisor with a MS Server 2012 R2 VM running Exchange 2013 patched to SP1. This server has been deployed into production and passing mail without issues for several months.
Upon initial deployment, we experienced the issue that many have reported and that has been widely documented where Mail Flow works fine inbound, but outbound will stick in the drafts folder. We resolved the issue by manually configuring the IP Address of our internal DNS server (which is an installed role on our hypervisior / base layer server). The issue was immediately resolved and mail was flowing in both directions without issue. We later installed SP1 and there was no issue. Mail has been flowing normally all the while.
Now fast-forward through several weeks of reliable mail delivery... We experienced a power loss and a system shutdown and upon reboot, inbound is working and outbound goes to drafts. I've confirmed DNS Lookup settings in ECP still points to our internal server as previously configured. Both servers have internet access, NSLOOKUP returns expected values, and DNS appears to be working normally.
I'm not sure if we had an MS Update that installed with the reboot that caused the breakage, if there was a lingering settings change that took effect on reboot, or what is causing the interruption. I'm looking for some fresh ideas on where to look for answers, and all the information available on the drafts folder issue points to DNS settings that have already been put in place.
Any constructive ideas are welcome! Thanks in advance.
David