Now they're caching each image once for all users, which pretty much defeats that.
Re:Gmail was down
by schrodinger on Saturday January 25, 2014 @12:10AM
(#7119940)
Not really, now you just have to have a unique image URL for each email you send. How could they possibly tell they are the same image before downloading them?
Also they seem to engage in very spammer-friendly activities such as notifying spammers if and when you read their spam email (if images are turned on by default). Soooo, I can't imagine that competing against their spam filtering is as impossible as people tend to believe.