Google starts moving to Gmail mobile userspropelling movement .
Secret mode allows the sender to set the expiration date of the message, the recipient will not be able to forward the message, can not paste copies, can not download and print mail. The date set by the sender can be a week, a month or a few years, and the sender can also ask the recipient to confirm his identity through a one-time password received by SMS. The recipient receives the confidential email first and then logs in again to browse. The browsing mode disables copy-and-paste and printing, but you can still use screen shots.