http://www.iykpqm7jiradoeezzkhj7c4b33g4hbgfwelht2evxxeicbpjy44c7ead.onion/deeplinks/2018/02/how-congresss-extension-section-702-may-expand-nsas-warrantless-surveillance
If that number was an NSA selector, your email would have been collected, though neither you nor the email’s recipient was an NSA target. Have you ever mentioned someone’s email address through a chat service at work? If that email address was an NSA selector, your chat could have been collected, too.
“About” collection involves scanning and collecting the contents of Americans’ Fourth Amendment-protected communications without a warrant.