SDP Notification: ERROR : Mail dropped

We are receiving a number of emails that are sporadic on which users replies to tickets will drop the email. Unless the user CC's a technician the mail is obviously inaccessible as it is deleted once the process completes. If a ticket is created by a user and a response is sent to that user everything is fine. When the user tries to reply to the response and makes no changes to the subject or anything else we receive the notification "SDP Notification: ERROR : Mail dropped" And the reason comes in that the SDP On-Demand was stopped " messageid : .
Mail Fetching process of ManageEngine ServiceDesk Plus On-Demand was stopped.
Please resend the mail if needed.."

No one else in our organization uses the admin features of the system other than myself and I am never in stopping nor starting the mail fetch process. We have tried deleting the user from SDP and re-adding them to no avail. This started a couple of months ago and we have been trying to identify what is happening but with it being all over the board on when it works and when it doesn't we are stumped...