Is Outlook email encrypted?
No. Microsoft can read your Outlook.com email. The paid Encrypt option keeps a message inside Microsoft 365 and away from other providers, but readers open it with just a sign-in or passcode, so Microsoft can unlock it too.
Checked on 25 October 2026 against 5 sources.
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- Between its own usersMicrosoft can read itMicrosoft can open your mail, and while it doesn't say who holds the keys for the paid Encrypt option, readers open those messages with just a sign-in or passcode, so Microsoft's servers can unlock them too.1, 3
- To other servicesMicrosoft can read itBy default Outlook.com only encrypts the connection with TLS, and with Encrypt, people on other services sign in or use a passcode to read the message from Microsoft 365.1
- Stored mailboxMicrosoft can read itMicrosoft's privacy statement says it may access the content of your Outlook.com emails, for example to stop spam or to comply with the law.3
- Post-quantumNot yetNo post-quantum protection announced as of 25 October 2026.
- Who holds the keys
- Microsoft holds the keys to your mailbox, and while it doesn't say who holds them for the Encrypt option, its servers unlock those messages for readers who only sign in or enter a passcode.
- What Microsoft can still see
- Everything in your mailbox: messages, attachments, subject lines, contacts, and who you write to and when.
On business plans, admins can set up S/MIME, where each person keeps their own private key, which Microsoft recommends when true peer-to-peer encryption is needed.
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Can Microsoft read my Outlook email?
Yes. Outlook.com encrypts the connection when it sends mail to other providers1, but Microsoft can open what is stored in your account. Its privacy statement says Microsoft may access the content of your Outlook.com emails when it believes this is needed, for example to comply with the law or to prevent spam3.
Microsoft also says it does not use what you say in email to target ads3.
What does the Encrypt button in Outlook do?
With a Microsoft 365 Personal or Family subscription, Outlook.com and new Outlook for Windows add Options › Encrypt when you write a message1. Encrypt keeps the message inside Microsoft 365, and Do Not Forward also stops it being copied or forwarded1. People on other services read it through a Microsoft portal, signing in with their Google or Yahoo account or using a passcode sent by email1.
Microsoft says this is useful when you don't trust the recipient's email provider1. It doesn't say who holds the keys. But because a reader can open the message with just a sign-in or an emailed passcode, and no key of their own, Microsoft's servers must be able to unlock it. For its business email encryption service, which uses a similar portal, Microsoft says it manages and stores the keys2.
Can I use S/MIME with Outlook.com?
Not on a personal account. Microsoft's S/MIME setup guide is for work or school accounts, and its feature table says personal Microsoft accounts can't send digitally signed messages4, 5. S/MIME also needs a certificate for you4 and the public key of each person you write to2.
On work accounts, Microsoft recommends S/MIME when you need true peer-to-peer encryption2.
How Outlook compares
Sorted by how many parts are sealed by default, then by how many can be. Ties go A to Z.
Sources
- Send encrypted messages with a Microsoft 365 personal or family subscription, Microsoft. Read on 25 Oct 2026.
- Email encryption in Microsoft 365, Microsoft. Read on 25 Oct 2026.
- Microsoft Privacy Statement (last updated September 2026), Microsoft. Read on 25 Oct 2026.
- Set up Outlook to use S/MIME encryption, Microsoft. Read on 25 Oct 2026.
- Learn about securing and protecting email messages in Outlook, Microsoft. Read on 25 Oct 2026.
Changes to this answer
- First published.