We have user that has in two different Hybrid exchange environments an account. Within Outlook there is configured for both the exchage enviroments an account. Exp. email@example.com and firstname.lastname@example.org. When the user sends a mail from email@example.com to a recipient in @contoso.org she gets a non deliverable message with the error Remote Server returned '550 5.1.11 RESOLVER.ADR.ExRecipNotFound; Recipient not found by Exchange Legacy encapsulated email address lookup .
When she send the same mail from firstname.lastname@example.org to a recipient in @contoso.org there is not a problem.
It seems that the X500 adres wil be used, but the @exchange.org environment doesn't know the X500 adress from @contoso.org.
Does some one knows how we can disable the possibility that outlook uses the X500 addresses but only the smtp adress