Google redesigned the web version of Gmail last spring,and a new look. One of Gmail's new tools was the Confidential Mode, which allows you to set an expiration date or revoke access to confidential emails that the recipient can not forward, copy, print, or download. Now you can send . How it works:
Sending and receiving Confidential Gmail messages
To send a private email, open the Gmail app and tap the red button as usual, then tap the button . in the upper right corner and then tap Confidential Mode .
In private mode, you have two options: Set expiration date and password protection.
The expiration date is more like an expiration date. You can choose to have your confidential emails expire in one day, one week, one month, three months or five years.
There are two options for password protection: standard and SMS password.
Standard allows Gmail recipients to see the contents of their confidential e-mail directly in the body of the e-mail without a passcode. For other email clients, they receive a link in the body of the email, which then sends them a passcode to open their confidential emails.
If you choose an SMS passcode, you must provide a phone number when sending your confidential email. Then all recipients – Gmail or others – will receive a text with the code required to open the message.  For each confidential e-mail, the recipient will be notified in a field below your message that the message is due to expire on a specific date and options to forward, download or copy the content and attachments of the e-mail are disabled.
You do not have to wait until the expiration date to cancel access to a confidential e-mail that you sent. Just go to your Sent folder in the Gmail app, open a confidential email, and tap the large, blue Remove Access button. The e-mail message remains in the recipient's Inbox, but it can no longer see its contents. If you revoke your e-mail address, you will find it again in your "Sent" folder and click on the large, blue renew access .
Watch the screenshot
As with anything on the internet, you're never 100% sure. While a trusted Gmail message prevents recipients from forwarding, downloading, and copying your message and its attachments, it can not be prevented from taking screenshots or photos of your messages and attachments.