Sometimes, you want to send someone a confidential email that is for their eyes only. Though there's no way to make an email truly secure, Gmail and Outlook both offer a way to prevent your emails from being forwarded.

Of course, someone could always screenshot your email and share it that way, but using Gmail and Outlook's forward prevention features is a simple way to try to protect your emails. Here's how to use them.

How to Prevent Email Forwarding in Gmail

Gmail has a feature called Confidential Mode that disables the forward, copy, print, and download functions for the recipient, if they use Gmail. Those who don't use Gmail will receive an email containing a special link to open the email in a browser—it's a bit less convenient than reading it in-line as you would on Gmail, but it gets the job done.

You can also set an expiry date for the email and lock it with a passcode received via SMS.

To use Confidential Mode on Gmail:

gmail confidential mode
  1. Compose an email.
  2. Click the Confidential Mode button in the bottom toolbar. It looks like a lock and timer.
  3. In the window that opens, use the Set Expiry dropdown to set an expiration date for the email. You must set an expiration date, so if you're not worried about the email remaining in the recipient's inbox, set the expiration date for the maximum of five years.
  4. Next, choose your passcode option. If you choose No SMS passcode, there's no additional protection. If you choose SMS passcode, you must enter the recipient's phone number so they can receive the passcode via SMS.
  5. Click Save. You'll see a message at the bottom of the email that indicates that you are sending a confidential email. To change these settings, click Edit. Alternatively, click X to remove Confidential Mode from the email.
  6. Compose the rest of your email as standard and click Send.

Related: How to Automatically Forward Emails From Outlook to Gmail

How to Prevent Email Forwarding in Outlook

You can send encrypted emails in Outlook, both the web version and desktop app, but the barrier to entry is far higher than Gmail. It's primarily designed for business users. That's because you need a S/MIME encryption certificate or an Office 365 Enterprise license. How to obtain the former is outside the scope of this article and is detailed on Microsoft's support website.

If you are set up for email encryption in Outlook, it means you can send messages which can only be opened by the intended recipients—and therefore can't be forwarded.

Related: How to Send Encrypted Email With 5 Popular Mail Services

Here's how in Outlook for desktop:

outlook encrypt email
  1. Compose an email.
  2. Click the Options tab.
  3. In the dropdown menu, select Do Not Forward.
  4. If you change your mind before sending the email, click Remove encryption.

And in Outlook on the web:

  1. Compose an email.
  2. Select the three horizontal dots icon and click Message options.
  3. Click Encrypt this message (S/MIME).

Keep Your Emails Safe and Encrypted

Remember, there's no such thing as an email that can only be seen by one person. That's because the recipient could distribute the email some other way, like with a screenshot or typing it out manually. If someone really wants to forward your email, they'll find a way, but the methods described here are a good first line of defense.

However, if email security is very important to you, perhaps consider using an email provider that puts your security first. ProtonMail is a famous example, but there are other services that will help keep your data and messages safe.