When enduser sends an email to help desk email box, an incident should be created.
The issue is Multiple duplicated incidents are created by inbound mail service and the mails in inbound mailbox are not marked as read.
So duplicated incidents are generated every 1 min. (If polling time is set to 1 min)
The trouble making email might contain an attachment, such as a .eml file. And the file size of the attachment might be over 3 MB.
The error message in Event Viewer looks like(It changes according to your environment):
Access to the path 'C:\Windows\TEMP\XXXX' is denied.
The TEMP folder is located:
When Inbound mail service try to modify files under TEMP, the Log on user of Inbound Service does not have modify right.
You may give that user the modify right of TEMP folder.
By default the log on user of Inbound Service is Local System account and does not have this issue. You may check the login info:
If you use other account as log on of Inbound Service, you may give that account modify right to TEMP folder.
Or you may set TEMP folder everyone modify right as below(If you concern about security, you may empty TEMP folder regularly):