[strogonoff]

I'm curious, how do you measure open rates for a newsletter? Many email clients prevent external content from loading as a security measure, thus precluding any tracking. Do you adjust the final figure to account for resulting underreporting? Or do you reckon more clients load external content than I think?

[mvellandi]

Open rates were measured (probably) from either track-pixels as well as any normal images hosted by the email provider. When an email is variably considered 'trusted'/not-spam by the client, it'll show images. But even if no images are shown, a link clickthrough in the email (to the email host and redirected to source) would then also be added to the open rate.