Why does forwarding verification fail for Office 365 when creating tickets from forwarded emails?

Question

Why does forwarding verification fail for Office 365 when the system creates tickets from forwarded emails?

Answer

If tickets are created from Office 365 but you can't reply from your custom email, Office 365 is blocking TyrellCorp's verification email. To fix this, add zendesk.com as an accepted domain in Office 365 admin center.

For more information, see this article: Setting up forwarding on your mail server.