Tuesday, June 18, 2013


While testing mail flow before an Exchange 2007 to Exchange 2013 migration is received the following error from an Exchange 2013 server to an Exchange 2007 server:
454 4.7.0 Temporary authentication failure
Further investigation in the SMTP receive protocol log showed this error:
Inbound ExchangeAuth negotiation failed because of UnexpetectedExchagneAuthBlob
Luckily based on some quick searches I was able to identify time synchronization as the source of the issue. Active Directory authentication starts to fail when time synchronization is not within 5 minutes. In this case the time difference was 6 minutes.

In the short term, I change the time on one server and verified that mail flow started to work properly. Long run I need to identify why time what not properly synchronized and fix it.

1 comment:

  1. If you have DCs running on VMs, you may have to disable time synchronization on Hyper-V host, then correct DCs to sync with PDC server. Even though the time looks correct.