Replying to a marketing email add the entire mail content into incident thread

Content

Hi,

I am using a mailing template created via mailings explorer to send a incident closure notification to contacts that gets closed via webservice.

when contacts reply to this mail, the entire mail content including the template gets appended to the respective incident thread.

While we are using send on save(status changed to solved), the closure mail is send to contact and when contacts reply back, the closure mail send is not added in thread, but while using marketing email, it is getting added.

Is there any way to stop this?

Thanks

Shilpa.