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Digital IDs, also known as digital certificates, help to validate your identity, and they can be used to sign important documents electronically. They can also be used to help protect messages by adding a unique code to the message called a digital signature. A digitally signed message proves to the recipient that you, not an imposter, signed the contents of the message, and that the contents haven’t been altered in transit.

To find services that issue digital IDs for your use, or services that complement Microsoft 365 and use digital IDs, check out the following websites. It's up to you which one you choose, and others are available that are not in this list, but these are some certificate authorities (CAs) that are qualified to issue digital certificates.

  • GlobalSign - To learn more about GlobalSign digital signatures, visit the GlobalSign website.

  • IdenTrust - To learn more about IdenTrust's TrustID Secure Email Certificates, visit the IdenTrust website.

  • DigiCert - To learn more about DigitCert client certificates, visit the DigiCert website.

Notes: 

  • A digital signature isn’t the same as a message signature, which is a customizable salutation. A digital signature adds unique code to a message which only comes from the digital ID held by the true sender.

  • Your organization may have its own policies and procedures for using digital IDs and certificates. See your network administrator for more information.

More about digital IDs and signatures

See also

Add or remove a digital signature in Microsoft 365 files

Send encrypted email messages in Outlook

View and reply to encrypted messages in Outlook

Secure messages by using a digital signature in Outlook for Windows

Get a digital ID

Send a digitally signed or encrypted message for Mac

Advanced Outlook.com security for Microsoft 365 subscribers

Learn about encrypted messages in Outlook.com

Encrypt messages using S/MIME in Outlook on the web

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