If you aren't receiving email into your CRM queues correctly, or your outgoing email doesn't seem to be sending please contact the Service Desk urgently!
Agent Only Info:
If users report emails are not sending or receiving please contact CRM personnel as a matter of urgency.
The email router does stop processing emails from time to time and is an ongoing issue raised with Microsoft. It is monitored via SCOM Alerts and is checked every morning by CRM Admin.