Fix GoogleImageProxy User Agent Parsing
In looking through some of the log events, I'm noticing a common User Agent string:
Mozilla/5.0 (Windows NT 5.1; rv:11.0) Gecko Firefox/11.0 (via ggpht.com GoogleImageProxy)
This appears to be a Google Image resolver, but unfortunately it's identified as a Windows Desktop. This incorrectly inflates those categories in my Open statistics.
Chris Moyer commented
According to Mailgun:
This is a known behavior. It is caused due to how Google caches images. A tracking pixel pic is used in the email to capture the open event. Gmail handles images by first submitting them through Google’s image proxy servers. So whenever an open occurs for Google mailboxes it logs the location on one of Google's servers.
This can be easily seen by querying the Logs, and checking the "client_type" and "client_device" fields that are parsed in Webhooks for Open/Closed statistics.