Our user agent data is gathered from contacts who have opened your emails. This allows us to parse related data about contacts' devices, OS, desktop email clients, and web browsers. However, when email clients such as Google and Yahoo are involved, they suppress the user agent string and encrypt it through proxy servers. We do not receive authentic data from these proxy servers, so we remove this user agent data from our stats. This can lead to discrepancies between the number of email opens and the user agent stats.