I have a strange issue, when REPLYING to another tenant on our Exchange server from Apple Mail or Outlook for Mac the message will not send, the recipients email address is replaced with: 'First Name' 'Last Name' </o=ServerName/ou=Org unit /cn=Recipients/cn=79093033052d4430b4fe4a935c36a8dc-'First Name' 'Last Name' >

The issue is not present in OWA or Outlook for PC, I have tried creating new users and fresh profiles in OSX.

Additionally I have tried:

Removal of all Contacts

Use of a fresh profile on a Macbook

Repair of Disk permissions on Mac

Disable Contacts app on OSX

Has anyone seen this issue before?

Hi,

For your description, I understand that the message cannot be sent when reply messages from Apple Mail or Outlook for Mac, however it works in OWA or Outlook for PC.
If I misunderstand your concern, please do not hesitate to let me know.

I want to confirm some points, please help collect answers for analysis:
1. How about send message from Apple mail or Outlook for Mac?
2. Is there any error message return after send message?
3. Do you have change any setting before this issue arise?
4. Whether all users with Apple mail or Outlook for Mac face this issue?

Please check the configuration for mail client, especially ports, SSL and authentication.
Also check the relevant error in event log with EWS.