David Johnson has sent more than 260 emails to Jay-Z, but has yet to receive a single reply. That may not mean his messages aren’t being read:

“‘[Jay] has opened every single one of my emails, even re-opening them to re-read,’ says Johnson. ‘He has clicked on links and had emails open for as long as 20 minutes.’ He knows this because he uses a tool called ReadNotify, which embeds a small, unique invisible image in every message he sends. When the message is opened, the image loads from ReadNotify’s servers, which record the time of the view, its duration and rough location. ReadNotify then gives the sender a read receipt, confirming that the message was seen. These services have been around for years, and they work — this kind of “bugging” is an old email marketing trick.”