Gmail Now Lets You Send Self-Destructing 'Confidential Mode' Emails From Your Phone (zdnet.com)
Google has rolled out its 'confidential mode' for setting a self-destruct date on email to mobile devices. From a report: Confidential mode came with the search company's big redesign of Gmail announced earlier this year and became the default for consumer Gmail users in July, while G Suite business customers still have a few months to make the switch. The data-protection feature is now available on mobile devices, Google announced via a tweet. Google promotes the Gmail feature as a way to protect sensitive information by allowing users to set an expiration date for individual messages or revoke access to messages already sent. The feature also prevents recipients from forwarding, copying, printing or downloading its content and allows users to require recipients to enter a one-time code sent via SMS to view the email. The authentication feature is intended to protect information in the event of the recipient's email account being hijacked. Further reading: Does Gmail's 'Confidential Mode' Go Far Enough?
No matter what kind of security Google places on this, it will always be possible for the recipient to save a copy for their own records. The brute force approach of simply taking a picture of the email with another phone/camera will always work. And that is before the hackers do their stuff. So don't trust this system to keep your messages truly confidential.
So it's not supposed to protect against a malicious recipient spreading snapshots of the email you sent them. It's supposed to protect against a lazy recipient not deleting the email as you requested, and a malicious third party getting access to it in the future when they hack the recipient's email account.