We have recently set-up a Windows Server 2012 R2 and integrated it with Office 365. Now we are getting DSN 5.1.x Errors when we cc the info email address of our company. I have logged on to the OWA and done a test and we do not get the error from there so it is only from Outlook on the computers in the office on the internal domain.
We have deleted the email address in the nickname cache in Outlook and manually added it but this did not work
Any suggestions welcome