"Source" already gives you the name of the device.  Hardware serial number also help you identify the device of interest.  You can just open the MobiControl web-console, and use either of the above to do a device search, and you can see all information associated with the device and its user (including any custom attributes you have added). 

If each of your devices is for dedicated use by one single end-user for an extended period of time,  one simple and quick way is to name the device systematically, possibly with the end-user's name, office phone number, staff number, etc, as the suffix(es) separated by understore.  Then, you, or someone with no access to the MobiControl web-console, can identify the end-user from the "source" field in the alert e-mail.  This is what I recommended for some of my customers with 3-party helpdesk support team that has no access to the web-console.