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-- Google Gmail Advertising
---- Gmail blows up e-mail marketing by caching all images on their servers
brotherhood_of_LAN - 6:52 am on Dec 13, 2013 (gmt 0)Thread source:: http://www.webmasterworld.com/gmail_advertising/4630311.htm
It's worth noting that the marketer can still see the first "open" by the user, and all images thereafter are cached.
A (temporary?) workaround is sending a content-length:0 HTTP header with the tracking image.
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