Incident Email listener is set up is to create a new incident and update existing incidents if you email into the specified email listener inbox. The following setup will allow you to only update existing incidents and will not create new ones.
How to Setup Email Listener to only Update Existing Incidents and not Create a New Incident
1. Log into the Admin Role
2. Select Configure Application
3. Go to Email Configuration
4. Go to Servers
5. In the tab "Inbox" click New
6. Follow the steps outlined in the help file, if needed, on creating an inbox: Creating an Inbox
7. For Email Processor - Select Other
8. Fill in the following values
a. NAME: Inc
b. Unique Key: IncidentNumber
c. Record Marker # (leave create Incident on Error check-box blank)
d. Field Value Separator: $
e. Leave Create Business Object on Error blank as well.