How to Send Encrypted Emails in Microsoft Outlook on Windows with a Microsoft 365 Subscription
If you’ve tried to send encrypted emails via Outlook, you know it can sometimes feel like trying to find a needle in a haystack. The interface isn’t always crystal clear—especially if your organisation manages your settings. But once you get the hang of it, it’s not too bad, and knowing where to look can save you a lot of hassle. If you’re on Windows and using a Microsoft 365 subscription, here’s what finally clicked for me when I was troubleshooting this late at night.
Starting a New Email in Outlook
First off, make sure Outlook is fully open — it’s surprisingly easy to forget to open the app or get distracted, only to wonder why some options are missing. Once Outlook’s up and running, hit the New Email button — usually at the top-left corner, or simply press Ctrl + N while inside Outlook. This opens a blank email window ready for you to compose. Sounds simple, right? Well, the tricky bit is finding the encryption settings.
Finding the Encryption Settings
This part took me a bit of trial and error because the encryption toggle isn’t always where you’d expect. In the new message window, look for the Options tab on the ribbon toolbar. Sometimes, especially on older hardware or if your Outlook is in simplified mode, it’s tucked behind a menu icon (like three dots). If you don’t see it, check whether your ribbon is collapsed or in a reduced view. The icon you need might be labelled Encrypt or represented by a padlock or shield symbol. Microsoft updates Outlook regularly, so the layout might vary depending on your version.
Sometimes you’ll need to jump into File > Options or Trust Center to check if encryption features are enabled. If the encrypt button is missing altogether, it could be due to organisational restrictions or missing add-ins. Occasionally, encryption options are greyed out or disabled—often because of policies set by your IT department. In such cases, you might need to update Outlook, install specific components, or seek permission from your IT support.
Selecting and Confirming Encryption
When you finally find the Encrypt button, clicking it will reveal a dropdown or modal with options. You might see choices like Encrypt, Encrypt-Only, or something related to Permissions. Select Encrypt. If your version supports it, you might see an option for Encrypt with S/MIME — which requires certificates — or Encrypt with Office 365. The idea is to mark your email as encrypted so only someone with the right setup can read it.
Once you choose your preferred encryption, a message will often appear at the top of your email saying “This message will be encrypted”—which confirms it’s set up correctly. Keep in mind, encryption depends on your account configurations. If the option is greyed out, it might be because policies restrict it. For S/MIME, you’ll need a valid certificate installed on your system, which you can manage under File > Options > Trust Center > Trust Center Settings > Email Security. There, you can import or generate certificates. For Office 365 message encryption, it’s more about matching policies on both sender and recipient sides.
Composing and Sending the Encrypted Email
With encryption activated, just finish writing your email — subject, message, attachments. When you’re ready, hit Send. If everything’s set up properly, Outlook will handle the encryption behind the scenes. You might be prompted to select a certificate if you’re using S/MIME. Otherwise, with Office 365, the message encrypts transparently, but the recipient’s email client must support encryption. If they don’t, they’ll struggle to open the message — irritating, but sometimes unavoidable.
An important tip: make sure the recipient’s email system supports encrypted messages. Otherwise, they’ll see garbled text or error messages. Also, if you’re using S/MIME, double-check that your certificates are installed and configured correctly under Trust Center > Email Security. You can generate self-signed certificates for trial purposes or obtain certificates from a trusted provider. Without valid certificates, S/MIME won’t do much.
Some Final Tips and Troubleshooting
Once you get familiar with the process, you’ll notice organisational policies can sometimes interfere — the encrypt button might be hidden, greyed out, or simply not there. If that happens, contacting your IT support is usually the best move. Also, bear in mind, your recipient needs to have the right setup too—matching certificates or permissions—to decrypt your message. While it’s not foolproof, it’s a lot safer than sending sensitive info in plain text.
If your Outlook looks different or options aren’t where I described, don’t worry — just explore the File or Trust Center menus. Sometimes, encryption features are located in unexpected places, especially after updates or if your organisation has customised the interface.
In Summary
At the end of the day, sending encrypted emails with Outlook on Windows and Microsoft 365 boils down to these steps: open a new message (Ctrl + N), go to Options, click the Encrypt icon, select your preferred encryption method, and then compose and send as usual. It’s a few extra clicks, but once you spot the toggle, it becomes second nature.
I hope this helps — it took me ages to figure out the quirks and policies. Make sure your account settings are correct, verify certificates if you’re using S/MIME, and ask your IT team if something doesn’t look right. Hopefully, this saves someone a weekend or at least a few hours of head-scratching. Good luck!