See explanation here:
http://community.spiceworks.com/how_to/show/1588-how-to-stop-and-prevent-ticket-loops-in-spiceworks
Essentially, the settings you need to alter are in Go to "Settings-> Email Settings -> Additional Settings".
and you need to add a rule in one of the "Ignore" fields.
These fields use Regular Expressions, so search for that on the web to understand how Regular Expressions work.
http://community.spiceworks.com/how_to/show/1588-how-to-stop-and-prevent-ticket-loops-in-spiceworks
Essentially, the settings you need to alter are in Go to "Settings-> Email Settings -> Additional Settings".
and you need to add a rule in one of the "Ignore" fields.
These fields use Regular Expressions, so search for that on the web to understand how Regular Expressions work.