To troubleshoot issue with email delivery to a specific domain in Outlook for Exchange:

1. Check that the intended recipient's email domain is receiving your emails, by sending a message to an email account outside of the domain.
2. Check the domain's MX records and verify that they resolve correctly.
3. Make sure that the domain has not been blacklisted.
4. Identify which mail server is used to send the email.
5. Check the domain's firewall and any other security measures.
6. Verify that the email messages are following the intended route to the intended mail server.
7. Ensure that the receiving mail server is configured correctly.
8. Check that there is sufficient disk space available on the receiving mail server.
9. Ensure that the sending mail server has not been blocked by the receiving mail server.