邮件追踪类的网站工具

1. https://www.yesware.com/

2. https://www.contactmonkey.com/

3. https://mailtrack.io/en/

4. https://www.bananatag.com/email-tracking/

5. http://www.didtheyreadit.com/

6. https://www.cirrusinsight.com/

7. https://www.saleshandy.com/