(Don't) Return to Sender: How to Protect Yourself From Email Tracking
There are a lot of different ways to track email, and different techniques can lie anywhere on the spectrum from marginally acceptable to atrocious. Responsible tracking should aggregate a minimal amount of anonymous data, similar to page hits: enough to let the sender get a sense of how well their campaign is doing without invading users’ privacy. Email tracking should always be disclosed up-front, and users should have a clear and easy way to opt out if they choose to.
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