How to encrypt emails in Outlook

Sasha Muller January 18, 2016

When it comes to sensitive data and personal information, you never can be too careful online. If you want to make sure that your email messages can’t be intercepted and read by a third party, then one option is to cryptographically sign your emails. As long as you’re using Microsoft Outlook 2003 or later, then it’s easy enough to do – and here’s how.

TOP TIP: The methods below won’t work if you access your email account via the Office 365 Outlook.com web portal. Unless your system administrator has installed the Office 365 Message Encryption plugin and set the necessary rules for automatically deciding which emails should be encrypted, your emails will be sent to their destination as is.

But, as long as you’ve got Outlook installed on your computer, you should be able to resort to the desktop client for all of your digital signing and encryption needs. The first step in the process is to set up your own personal digital signature.

Add a digital signature to your emails in Outlook

Both sender and recipient have to share their digital ID or public key certificate with each other. This means that both parties are able to trust each other’s authenticity and be sure that messages haven’t been intercepted and tampered with.
To set yourself up with a digital ID, go to File | Options | Trust Center, then click E-mail Security. Here, incidentally, you can tick the relevant boxes to enable encryption and digital signing for every outgoing email, or alternatively click “Get a Digital ID…” to see links to a selection of ID providers, including Comodo, which provides free email certificates.
If you’d rather sign an individual message, then make sure that you’ve left the digital signing tick box in step two unticked. Now open a new message. In the Message tab, click the Digitally Sign Message button. This looks like an envelope with a little gold rosette attached, just like the image above step one.
If this option isn’t available, then you’ll need to click Options Dialog Box Launcher in the bottom right of the Options group. This brings up the Message Options dialog box. Click the button labelled Security Settings, and tick the entry in the dialog box marked “Add digital signature to this message”.
Write your message and send it. Bear in mind that, if you want to send encrypted messages in the next step, you’ll need to get your email contact to send you a digitally signed email. Once you’ve received a signed email, right-click their name in the From box and select Add to Outlook Contacts option. If the person is already in your contacts, select the “Update information of selected Contact” option.

Encrypt email messages in Outlook

In the message you wish to encrypt, click the “Encrypt Message Contents and Attachments” button. This looks like an envelope with a blue padlock in its top-left corner.
If this option isn’t available, you’ll need to click Options Dialog Box Launcher in the bottom right of the Options group. This brings up the Message Options dialog box. Click the button labelled Security Settings, and tick the entry in the dialog box marked “Encrypt message contents and attachments”.
If you haven’t already written your message, do so now and send it. And don’t forget, if you’ve skipped straight to the encryption part of this tutorial, that you can only send encrypted messages between email addresses that are both digitally signed. Not sure what I’m talking about? Then read the walkthrough above.
To enable encryption for all outgoing emails, go to File | Options | Trust Center, then click E-mail Security. Here, simply tick the relevant box to enable encryption for all your emails.

Want to become an Outlook expert? Click here to check out our guide to the ultimate Outlook tips and tricks.