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How to Send Documents Securely via Email

Published by David on
email showing a gmail attachment looking like a safe vault

Have you ever sent an important document via email while doubting the security level of your messaging service? 🤔

We have. And we decided to take the necessary steps to never doubt again.

There are several ways to encode documents, but these methods are complex. We're not NASA engineers! 🚀

Moreover, encoding documents only protects the transit of information. It doesn't guarantee anything about what the recipient can do after receiving it.

That's why we prefer a simple method with Gmail while keeping security on your files even after they've been sent.

How to Send Secure Email Attachments in Gmail, the Simple Way

We offer you two options that you can use separately or combine together.

Method 1: Assign File Access Permissions with Google Drive

The goal is to give specific rights to the recipient of the file. You remain the owner of the file:

  1. Upload your document to Google Drive.

  2. Click on the file, then on "Share".

  3. Enter the email addresses of the recipients.

  4. Define their rights: "View only", "Comment", or "Edit".

  5. Send the email with a link to the file.

 

You keep full control! You can modify and revoke access at any time. Plus, you can track user actions on the file via the history of modifications or views.

💡 The little extra that changes everything: did you know that if you use the Mail Merge application, you can still use this technique to secure your files?

 

Method 2: Send a Secure Email with Gmail's Confidential Mode

Instead of securing only your document, you secure the entire email.

Gmail's confidential mode offers several levels of security:

  • You set an expiration date after which the message becomes inaccessible.

  • You can revoke access to the message at any time, even after sending it.

  • Recipients' actions are limited: they cannot forward, copy, print, or download the email's content or its attachments.

💡 Note: Confidential mode does not prevent recipients from taking screenshots or photos of the message. Moreover, emails are still accessible to Gmail administrators.

It's very simple to use:

  1. Click on "Compose".

  2. Click on the icon that represents a padlock with a clock.

  3. Choose the duration during which the message will be accessible (1 day, 1 week, 1 month, 3 months, or 5 years).

  4. Choose the passcode mode:

    • Without passcode: Recipients using Gmail can open the message directly. Those not using Gmail will receive a passcode by email.

    • With passcode: All recipients will receive a passcode via SMS. You will need to enter the recipient's phone number when sending.

  5. Click on "Save".

  6. Send the email.

  7. If you chose the passcode, enter the recipient's phone number when prompted.



⚡ Note: Outlook also offers a similar process.

Do you now want to know the methods used by NASA engineers? 😉

Alternatives Way to Email Confidential Documents

End-to-End Email Encryption (E2EE)

Only the sender and the recipient can decrypt the content of an email thanks to an encryption key. Messages are converted into encrypted text that is unreadable to anyone else.

 

➕ Advantages:

    • Files sent with the email are also encrypted.

    • Even if the email server is hacked, encrypted messages remain protected.

➖ Disadvantages:

    • Complexity for the user.

    • Loss of the key makes messages unrecoverable.

    • Not all email services offer it.

💿 Main email encryption protocols:

    • S/MIME: This feature is available for Gmail users with Enterprise, Education Fundamentals, Education Standard, Teaching and Learning Upgrade, and Education Plus editions.

    • PGP/MIME: To encrypt emails on Android devices, a third-party app is necessary, such as OpenKeychain.

Email Services with Native Encryption

An email service with native encryption applies end-to-end encryption (E2EE) automatically, without having to manually manage encryption keys.

➕ Advantages:

    • Simplicity of use.

    • Multi-platform accessibility.

    • Compliance with strict regulations like GDPR.

➖ Disadvantages:

    • Limits exchanges with users of other non-secure platforms.

    • Cost of advanced features or for more storage.

    • Restricts integration with third-party tools due to encryption.

💿 Examples of platforms:

Protect Your Documents with a Password

Adobe Acrobat and Microsoft Office offer this option.

Microsoft Word, Excel, PowerPoint Documents

This is possible with the desktop versions for Windows and Mac, but not with the web version Office Online.

Here is the detailed procedure for Windows:

  1. Go to File > Info > Protect Document > Encrypt with Password.

  2. Enter a password and click OK.

  3. Enter it again, then click OK.

  4. Save the file to ensure the password is applied.

Whenever someone opens the protected document, Word displays a dialog box prompting you to enter the access password.

💡 Note: Protection methods and security levels may vary depending on the Office versions.

 

 

Adobe Acrobat PDF Documents

This feature is not available with the free version of Adobe Acrobat.

On Windows, simply follow these steps:

  1. Open the PDF document. Select All Tools > Protect a PDF > Protect with a Password.

  2. In the dialog box that opens, indicate whether you want to set a password to view or to edit the PDF. Here, we want a password to manage opening the file, so select "View".

  3. Enter the password, then enter it again and click Apply.

 

On Mac devices, you just need to use the Preview application:

  1. Open the PDF with the Preview application (default on macOS).

  2. Click on File > Export > Encrypt or Protect with Password.

  3. Enter and confirm the password.

  4. Click on Save.

 

💡 Note: You cannot add passwords to a signed or certified document.

Require a Signature Upon Receipt

There are many online platforms to obtain electronic signatures for your documents.

⚙️General process:

    • Create an account.

    • Upload your document to the platform.

    • Add a signature field in the document.

    • Enter the recipients' contact information.

    • Send a signature request.

    • The recipient signs the document.

 

➕ Advantages:

    • Speed

    • Traceability and security

    • Legal compliance

 

➖ Disadvantage: Cost

 

💿 Examples of platforms:

Expert's Eye: Is Gmail Reliable for a Professional Context?

Unless you work in national defense, Gmail is a reliable option for most professional contexts.

Indeed, it uses TLS (Transport Layer Security) encryption to protect data transmitted between the sender and the recipient. However, as we have seen, end-to-end encryption is not supported natively.

The advantage of Gmail in a professional context is its compatibility with soooooooooo many third-party tools.

👉For example, Mail Merge is specially designed for Google Sheets and Gmail. A complete documentation explains precisely the features of this simple and free tool, which you can try for free, without commitment, without registering a credit card. 

It's the best extension for bulk email. It notably allows you to send attachments, which you can secure as we've seen in this article.

 

 

👉Similarly, Mail Tracker for Gmail indicates by its name that it was specifically developed for Gmail.

 

Conclusion

The security of your documents doesn't have to be complicated. With Google Drive, you can easily share files while keeping control over who can view them. And if you prefer, many alternatives exist to protect your sensitive data.



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