Exchange 2013 mail stuck in draft - Mailbox Transport Submission service failing to start

We just recently begun building an Exchange 2013 DAG to support out email environment. This is part of an internal shift to Lync 2013 and Exchange 2013 for unified communications. We followed Microsoft instructions on building my first 2013 machine, migrated a single test mailbox and started testing.

We found no mail flow between the Exchange 2013 and Exchange 2010 environments, all email sent from 2013 OWA or Outlook was just sitting in the drafts folder. In fact even if I emailed within mailboxes on the 2013 mail database they would also stay in drafts.

Upon investigating this problem there was a failure of the "Microsoft Exchange Mailbox Transport Submission", "Microsoft Exchange Transport" and "Microsoft Exchange Frontend Transport" services.



The Problem

Windows application event logs showed the following errors when trying to restart the "Microsoft Exchange Mailbox Transport Submission" service.

Log Name: Application
Source: Application Error
Event ID: 1000 

Faulting application name: MSExchangeSubmission.exe, version: 15.0.712.12, time stamp: 0x51aff4c9
Faulting module name: unknown, version: 0.0.0.0, time stamp: 0x00000000
Exception code: 0xc00000fd
Fault offset: 0x000007fb0b3cc301
Faulting process id: 0x2894
Faulting application start time: 0x01ceaa8fd8cefada
Faulting application path: C:\Program Files\Microsoft\Exchange Server\V15\Bin\MSExchangeSubmission.exe
Faulting module path: unknown
Report Id: 179beb57-1683-11e3-93f5-00155dd80a77
Faulting package full name:
Faulting package-relative application ID: 

There is also another event log with some more telling information.

Log Name: Application
Source: MSExchangeTransportSubmission
Event ID: 7010 

The activation of modules are taking longer than expected to complete. Current state of components:<LoadTimings>
....
  <Component Name="Dns" Elapsed="00:00:23.1781923" IsRunning="true" />
</LoadTimings>
<StartTimings />
<StopTimings />
<UnloadTimings />

It is indicating that the DNS component was failing to start in a timely manner.



The Resolution

We checked and double checked our DNS, no issues. We also followed a number of blogs that indicate you need disable IPv6 and manually select the network adapter under DNS lookups on the Exchange server properties. We did this to no avail, however the actual resolution wasn't far off.

1. Open Exchange 2013 ECP
2. Go to "Servers" tab
3. Select "servers" from across the top menu
4. Double click the problematic server from the list of Exchange servers
5. Select "DNS lookups"
6. Instead of selecting your network adapter, select "Custom settings" under "External DNS lookups"
7. Add all your DNS servers
8. Repeat the same for "Internal DNS lookups"
9. Restart the above failing transport services
10. Rejoice

This seems to be a bug with a .NET 4 module Microsoft.Exchange.Net.ni.dll. Selecting "Custom settings" bypasses this .NET bug.

If you are still having issues with mail flow, ensure your new Exchange 2013 server has a system mailbox and consider removing the Exchange 2013 server, wiping AD clean and starting a fresh install.