Users in different departments have reported intermittent issues with emails not being received, or taking a week to reach the destination. This is with regards to email being sent to the user, and also for email being sent out of the building.
The common complaint is that they send the email and it never is received. There is no error message related to delivery failure.
Sometimes the undelivered email contains attachments, sometimes it does not.
Not sure where to being troubleshooting, assistance would be appreciated.