Hi Kevin96706,
When you mention “There is a field on this object that says "Set the external email address". But this address is WRONG”, do you mean the address is not the same as the mailbox address in Exchange server or display messy code? I’d appreciated it if you can capture a screenshot of “Set the external email address”page and also provide information about the local mailbox in private message. As far as I know, the target address cannot be changed from Office 365 side. We may need to change the local mailbox address, and sync to Office 365. But incoming emails to the original user will not be delivered.
To see the private message, please perform the following steps:
1. Please go to "Your details" section on the right side of the community site.
2. Click Private messages.
3. Click the subject title <Please provide the service request number> of the response to read the message.
Thanks,
Johnny Zhang