You can send messages and attachments with Gmail's confidential mode to help protect sensitive information from unauthorized access. You can use confidential mode to set an expiration date for messages or revoke access at any time. Recipients of the confidential message will have options to forward, copy, print, and download disabled. 

Note: Although confidential mode helps prevent the recipients from accidentally sharing your email, it doesn't prevent recipients from taking screenshots or photos of your messages or attachments. Recipients who have malicious programs on their computer may still be able to copy or download your messages or attachments.

Send messages & attachments confidentially

1. On your computer, go to Gmail.
2. Click Compose.
3. In the bottom right of the window, click Turn on confidential mode .Tip: If you've already turned on confidential mode for an email, go to the bottom of the email, then click Edit.
4. Set an expiration date and passcode. These settings impact both the message text and any attachments. 
   • If you choose "No SMS passcode," recipients using the Gmail app will be able to open it directly. Recipients who don't use Gmail will get emailed a passcode.
   • If you choose "SMS passcode," recipients will get a passcode by text message. Make sure you enter the recipient's phone number, not your own.
5. Click Save.

Remove access early

You can stop your recipient from viewing the email before the expiration date.

1. On your computer, open Gmail.
2. On the left, click Sent.
3. Open the confidential email.
4. Click Remove access.

Open an email sent with confidential mode

If the sender used confidential mode to send the email:

• You can view the message and attachments until the expiration date or until the sender removes access.
• Options to copy, paste, download, print, and forward the message text and attachments will be disabled.
• You might need to enter a passcode to open the email.
• Open the email.
• If sender does not require a SMS passcode:
  • If you use the latest Gmail apps (web or mobile), you will directly see the email when you open it.
  • If you use another email client, open the email, click on the link View the email and sign in with your Google credentials to view the message.
• If sender requires a SMS passcode:
  • Select Send passcode.
  • Check your text message for the passcode.
  • Enter the passcode, then select Submit.

I'm getting an error

• The email has expired: The sender might've deleted the email or removed your access before the expiration date. Contact the sender to give you more time or to resend the email.
• Switch Accounts: Make sure you're signed into the correct Google Account that's associated with the recipient email. Then, try to open the email again.