Know when your emails are read.
Doesn't work.
"Your free trial expires today" popup spam
Does not work on my android 9 device and win 7 PC. Repeatedly asks for gmail log in, but without any success. Used to work earlier on my phone.
https://emailtracker.website/
https://getmailtracker.com
https://mailerplex.com/
https://canarymail.io
https://trekspeks.ru
https://www.free-email-tracker.com/
https://getprospect.com/
https://snov.io
https://getsonar.co
https://mailseen.com
Social Analyzer
https://digitalinspiration.com