How to Open an Encrypted Email in Outlook, Gmail, and Other Apps

To open an encrypted email, start in the inbox that received it. Depending on the message, you may be able to read it directly in Outlook, verify your identity through a browser link, enter a one-time code, or use an S/MIME certificate. The prompt you see tells you which method to use.

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9 min read
Christin Baumgarten

Operations Manager

Oliver Jackson
Reviewer

Head of Customer Happiness

Jose Lopez
Tester

Head of Growth Engineering

Authored By Christin Baumgarten Operations Manager

Christin Baumgarten is the Operations Manager at Mailbird, where she drives product development and leads communications for this leading email client. With over a decade at Mailbird — from a marketing intern to Operations Manager — she offers deep expertise in email technology and productivity. Christin’s experience shaping product strategy and user engagement underscores her authority in the communication technology space.

Reviewed By Oliver Jackson Head of Customer Happiness

Oliver is Mailbird's Head of Customer Happiness, bringing more than a decade of experience in email. His background in email marketing, where his strategic and creative approach to campaigns drove growth and engagement for businesses across diverse industries, shapes how he helps people get more out of their inbox. Oliver is known for his insightful webinars and guest posts, where he shares his expert knowledge.

Tested By Jose Lopez Head of Growth Engineering

José López is a Web Consultant & Developer with over 25 years of experience in the field. He is a full-stack developer who specializes in leading teams, managing operations, and developing complex cloud architectures. With expertise in areas such as Project Management, HTML, CSS, JS, PHP, and SQL, José enjoys mentoring fellow engineers and teaching them how to build and scale web applications.

How to Open an Encrypted Email in Outlook, Gmail, and Other Apps
How to Open an Encrypted Email in Outlook, Gmail, and Other Apps

To open an encrypted email , start in the inbox that received it. Depending on the message, you may be able to read it directly in Outlook, verify your identity through a browser link, enter a one-time code, or use an S/MIME certificate. The prompt you see tells you which method to use.

Key takeaways

  • Start in the inbox that received the message.
  • A “Read the message” notification may require a Microsoft browser-portal sign-in or passcode.
  • Gmail confidential mode and Gmail’s encrypted-message flow have different prompts.
  • An S/MIME-encrypted message needs the private key that matches the certificate for your receiving address.
  • If you did not expect a message, confirm it with the sender using contact details you already trust.

What does the email look like?

What you see What to do
A message in Outlook with a lock icon or restricted-permissions notice Open it in the Outlook account that received it. [2]
A notification with a “Read the message” link Check that the notification is genuine, then follow the Microsoft browser-portal sign-in or passcode prompt. [2]
A Gmail confidential message with “View the email” or “Send passcode” Follow the confidential-mode prompt. This is different from Gmail’s encrypted-message flow. [3] [4]
A Gmail invitation with “View message,” or an “Encrypted message” label Follow the address-verification, sign-in, or guest-access prompt. [4]
A certificate or smart-card prompt Use the S/MIME certificate and matching private key configured for your account. [5]
What you see
A message in Outlook with a lock or restricted-permissions notice
What to do
Open it in the Outlook account that received it. [2]
What you see
A notification with a “Read the message” link
What to do
Check that the notification is genuine, then follow the Microsoft browser-portal sign-in or passcode prompt. [2]
What you see
A Gmail confidential message with “View the email” or “Send passcode”
What to do
Follow the confidential-mode prompt. This is different from Gmail’s encrypted-message flow. [3] [4]
What you see
A Gmail invitation with “View message,” or an “Encrypted message” label
What to do
Follow the address-verification, sign-in, or guest-access prompt. [4]
What you see
A certificate or smart-card prompt
What to do
Use the S/MIME certificate and matching private key configured for your account. [5]

Before opening a link: If you did not expect the message, confirm it with the sender using contact details you already trust. Never share a sign-in or one-time code.

How to open an encrypted email in Outlook

Outlook desktop

  1. Go to the mailbox that received the message and open it in its own window if the reading pane does not display the contents.
  2. If asked to verify your credentials, sign in with the receiving account.
  3. Read the message in Outlook. You should not need to open an .rpmsg attachment yourself for a supported Microsoft-protected message. [2]

Outlook on the web

  1. Sign in to the Outlook mailbox that received the email.
  2. Open the message. If the reading pane does not show it, try opening it in a separate window.
  3. If you are asked for an S/MIME control or certificate, follow your organization’s setup instructions. A portal passcode will not replace an S/MIME private key. [2] [5]

How to open a Microsoft-protected message from Gmail or another app

If the message arrived as a notification rather than readable email, first verify that it came from the expected sender. Then:

  1. Select Read the message or Read your message .
  2. On the browser page, choose an offered sign-in option for the address that received the email. Available options can vary.
  3. If offered a one-time passcode instead, request it, return to the receiving inbox, and enter the new code on the browser page where you requested it. Select Continue .

The protected message opens in the browser, not necessarily inside Gmail or your other email app. Microsoft passcodes expire after 15 minutes; request a fresh code if yours has expired. [2]

How to open a secure email in Gmail

Gmail confidential mode

Open the message in Gmail. If prompted, select Send passcode , enter the code sent to your phone, and select Submit . If the notification arrived in another email app, select View the email and follow its code prompt. The sender can set an expiration date or remove access. Confidential mode is not the same as Gmail’s encrypted-message flow. [3] [4]

Gmail encrypted-message invitation

If the notification says View message , select it and follow the address-verification prompts. You may need to retrieve a code from your inbox and sign in with a Google account or create a guest account, depending on the sender’s organization. If the message already appears in Gmail with an Encrypted message label, open it and complete any identity-provider sign-in prompt. [4]

What if the message asks for an S/MIME certificate?

Open it in an account and app configured for S/MIME . If prompted, allow access to your certificate store or use your smart card and PIN. To read an S/MIME-encrypted message, you need the private key that matches the certificate for your receiving address. If it is unavailable on your device, ask your IT team for help; the sender’s certificate or a portal passcode will not unlock it. Do not upload your private key to an unfamiliar site. [5]

How to open an encrypted email on a phone

In Outlook for iPhone or Android, tap the Microsoft-protected message in the receiving account first. For a portal notification, open its verified link and finish the sign-in or code steps in your phone’s browser. In Gmail, follow the confidential-mode or encrypted-message prompt you see. S/MIME in Outlook mobile requires the app to be configured for S/MIME and the appropriate private key to be available on the device. [2] [3] [4] [6]

If the encrypted email will not open

Problem What to try
No one-time code arrives Check the receiving inbox, spam folder, and any work-email quarantine. Ask IT to check for the code email if necessary. [2]
A Microsoft code is rejected Return to the original message and request a new code. Enter it on the corresponding portal page within 15 minutes. [2]
The browser shows the wrong account Choose the address that received the email on the sign-in page, or sign out of the other account and try the verified link again.
Classic Outlook says “Cannot read the item” Close and reopen Outlook. Microsoft says an issue it marked fixed may require more than one restart. If the error persists, try Outlook on the web or contact IT. [1]
Outlook shows message_v2.rpmsg instead of the email Update Outlook and try again. Microsoft documented an “Encrypt Only” issue affecting some classic Outlook recipients; if the updated app still cannot read the message, contact IT or the sender. [7]
An S/MIME certificate is missing Ask IT to restore or configure the certificate and matching private key for your account. [5]
A Gmail confidential message is no longer available It may have expired, or the sender may have removed access. Ask the sender to extend access or resend it. [3]
You can read the email but cannot forward, print, or download it Check for a protection notice. If you need a copy or different permissions, ask the sender rather than trying to bypass the restriction. [2] [3]
Problem
No one-time code arrives
What to try
Check the receiving inbox, spam folder, and any work-email quarantine. Ask IT to check for the code email if necessary. [2]
Problem
A Microsoft code is rejected
What to try
Return to the original message and request a new code. Enter it on the corresponding portal page within 15 minutes. [2]
Problem
The browser shows the wrong account
What to try
Choose the address that received the email on the sign-in page, or sign out of the other account and try the verified link again.
Problem
Classic Outlook says “Cannot read the item”
What to try
Close and reopen Outlook. Microsoft says an issue it marked fixed may require more than one restart. If the error persists, try Outlook on the web or contact IT. [1]
Problem
Outlook shows message_v2.rpmsg instead of the email
What to try
Update Outlook and try again. Microsoft documented an “Encrypt Only” issue affecting some classic Outlook recipients; if the updated app still cannot read the message, contact IT or the sender. [7]
Problem
An S/MIME certificate is missing
What to try
Ask IT to restore or configure the certificate and matching private key for your account. [5]
Problem
A Gmail confidential message is no longer available
What to try
It may have expired, or the sender may have removed access. Ask the sender to extend access or resend it. [3]
Problem
You can read the email but cannot forward, print, or download it
What to try
Check for a protection notice. If you need a copy or different permissions, ask the sender rather than trying to bypass the restriction. [2] [3]

If a link or sign-in page looks suspicious, stop and confirm the message with the sender through a separate, trusted channel.

Want one desktop inbox for everyday email?

Mailbird is a desktop email client . If a received message requires a Microsoft or Google security portal, follow that provider’s access steps above.

Download Mailbird for desktop at getmailbird.com.

Frequently asked questions

How do I open an encrypted Outlook email in Gmail?

Open the notification in Gmail, select its verified “Read” link, then use the offered sign-in or one-time passcode option. Read the message in the browser tab. [2]

Where will my one-time passcode arrive?

A Microsoft portal passcode goes to the email address used to request it. A Gmail confidential-mode prompt may instead direct you to a code sent by text or email, depending on the access method. [2] [3]

Do I need an S/MIME certificate for every secure email?

No. An S/MIME-encrypted message needs the matching private key. A Microsoft portal link or Gmail confidential-mode prompt uses a different access method. [2] [3] [5]

Can I open a Microsoft-protected email in Mailbird or another desktop inbox?

If it arrives as a protected-message notification, use its verified link and complete the access steps in the Microsoft browser portal. The notification itself may not contain the protected message body. [2] [8]

Sources

  1. Microsoft Support: Error when opening encrypted email in classic Outlook for Windows
  2. Microsoft Support: Open encrypted and protected messages
  3. Gmail Help: Send and open confidential emails
  4. Gmail Help: Learn about Gmail client-side encryption
  5. Microsoft Support: Set up Outlook to use S/MIME encryption
  6. Microsoft Learn: S/MIME for Outlook for iOS and Android
  7. Microsoft Support: Classic Outlook recipients unable to open “Encrypt Only” emails
  8. Microsoft Learn: Microsoft Purview Message Encryption