By default, IPv6 is enabled in Windows. If IPv6 addressing is configured to use link-local addressing, there is a time-based latency in delivering messages in Microsoft Exchange Server 2013. This occurs because the computer tries to resolve the IPv6 address record (AAAA record).
To resolve this issue, install the following update:
2961810 Cumulative Update 6 for Exchange Server 2013
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.
For more information about APIPA IPv4 and IPv6 link-local addresses, go to the following Microsoft website: