With this new add-on (available at https://www.inflectra.com/SpiraTeam/Downloads.aspx) you can connect to your company's email server and have the system scan for inbound emails from end users.
The system will then either create a new incident request in SpiraTeam or if the email is in response to a notification from the system, it will simply add the email contents as a new comment on the existing SpiraTeam item.