Gmail and Microsoft-hosted email will make a copy of the tracking, so we detect google "viewing" the email as the 'viewed-at' time (if we detect anything at all), and then Google/Microsoft host their own COPY of the tracking to the end-user (which means we don't get any tracking data).

Some emails don't come through to Event Temple as 'read' because some recipients may be using Gmail or hosted Outlook email accounts.

At the moment this is an unavoidable situation, but of course, as technology evolves this may change down the line.