Google is Testing Self-Destructing Emails in New Gmail (techcrunch.com)

The upcoming update to Gmail might include a feature which would allow users to send emails that expire after a user-defined period of time. From a report: Working on an email service is hard as you have to be compatible with all sorts of email providers and email clients. But it doesn't seem to be stopping Google as the company is now evolving beyond the simple POP3/IMAP/SMTP protocols. Based on those screenshots, expiring emails work pretty much like expiring emails in ProtonMail. After some time, the email becomes unreadable. In the compose screen, there's a tiny lock icon called "confidential mode." It says that the recipient won't be able to forward email content, copy and paste, download or print the email.