It doesn't even mask repeat opens: as buro9 found in the sister comment, the ima...

		vilhelm_s on Dec 12, 2013 \| parent \| context \| favorite \| on: Gmail blows up e-mail marketing by caching all ima... It doesn't even mask repeat opens: as buro9 found in the sister comment, the image does not get cached, Google's proxy will request it again each time it is viewed.