I have an environment with 3 exchange servers. 2 of them have CA, MBX and HT roles, and 2 databases in 1 DAG. The other one is the Witness Server, only running HT role. This is all running on Windows 2008R2.
I recently migrated from another exchange forest in order to fix the internal domain name which was setup incorrectly as a single label domain name.
Everything is working well currently, except that once in a while, a user using OWA will email a distribution group and the email will bounce back with a #550 5.1.1 RESOLVER.ADR.ExRecipNotFound; not found ## error. If the user tries again the next second, it will go through. Upon checking out the bounce message I can see that the name of the distro group is not being resolved correctly and it displays the legacyExchangeDN name.
I don't understand why that happens when using OWA, which means they are not using any cache and I don't understand why this happens one second, but the next second it resolves correctly. Can anyone help?