An article from

Update: Gmail Image Blocking And Caching

If you haven’t already heard, Gmail will now start displaying images within emails by default, instead of blocking them by default as in the past. This means more accurate reports of email opens from Gmail subscribers. Initially, the change also meant repeat opens by the same subscribers would not be communicated, but our devs cracked [...]
Recommended Reading
-
Update: Gmail Image Blocking And Caching
AWeber Email Tips