How is geolocation tracked?
Geolocation works by capturing the IP address from the open made on the email. The IP is looked up by our system and the location is recorded, and then the IP address is discarded.
Many ISPs may not provide the exact town/city locations with the IP addresses. Laptops may also cache the IP from your previous location and may not have updated. Mobile opens made on a mobile data network (not using wifi) can be tracked differently. For apps running on a mobile device, the apps can use GPS and cell tower triangulation to determine the location. For an image loading in an email client, the IP is the same IP everyone else on that network in that area is using. AT&T in Boston, for example, is routed via New York and that is where the IP's location shows up.