IMCEAX error after migration from Exchange 2007 to Exchange 2013

There was an error while replying or sending e-mails to migrated user getting the following NDR:

Diagnostic information for administrators:Generating server: HUB.lab.local


#550 5.1.1 RESOLVER.ADR.ExRecipNotFound; not found
##Original message headers:
Received: from MAIL.lab.local ([]) by ....
  • Cause

LegacyExchangeDN is used to route mails within organization and after migration old LegacyExchangeDN was missing.

  • Solution

Add X500 address to e-mail addresses of migrated mailbox pointing to OLD legacyExchangeDN from NDR user have received.

EAC add X500

EAC add X500

  • The format of X500 address is well described here:

  • From our example


UPDATE: The last part of X500 should be user alias so unlessĀ  @domain.local isĀ part of your alias, it should be without @domain.local. I just have had and example, where this mattered.