Below are some steps to troubleshoot issues with emails not being delivered to a specific distribution list in Exchange:

1. Access the Exchange admin center in order to view and identify issues with mail flow.
2. Check if there are any settings that can interfere with emails being delivered, such as banned words, max size, or mailbox quotas.
3. Look for any generic emails that might be being sent.
4. Check the Exchange server settings and the message trace.
5. Check the Exchange organization settings.
6. Check if the distribution list is set up properly.
7. Ensure that the distribution list is accessible to those sending emails.
8. Verify if there are restrictions to certain domains.