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Receiving Encrypted and Digitally Signed E-Mail

  • Article

Applies to: Office 365 for professionals a, Office 365 for enterprises, Microsoft Exchange

After you've installed the S/MIME control on your computer and have obtained a digital identification (ID) from your system administrator, you can read encrypted messages.

How do I read an encrypted message?

  • Encrypted messages will have a lock icon Encryption icon next to the subject in the message header.
  • When you receive an encrypted message, Outlook Web App will check whether the S/MIME control is installed and whether there is a digital ID available on your computer. If the S/MIME control is installed and there is a digital ID available, the message will be decrypted.
  • If a valid digital ID isn't found, a warning will appear in the message header stating that you must provide a valid digital ID to read the contents of the message. If your digital ID is on a smart card, you may be prompted to enter a PIN to decrypt the message.

How do I verify the signature of a digitally signed message?

  • When you receive a message that has a digital signature, you can verify that the messages hasn't been tampered with and also the identity of the sender.
  • The list view will include an icon digital signature icon next to the message that indicates the message has been digitally signed.
  • The message header will include a link to more information about the status of the digital signature. By clicking the More information link, you can view the status of the digital signature in addition to other information about the sender and the digital ID used to digitally sign the message.
    A digital signature can have one of three states.
    • The digital signature on this message is valid and trusted indicates the digital signature was verified.
    • The digital signature on this message isn't valid or trusted indicates the digital signature verification failed with an error.
    • The digital signature on this message couldn't be verified indicates the digital signature couldn't be verified. No additional information is available.

What else do I need to know?

  • The S/MIME control is necessary to verify the signatures of digitally signed messages. If you receive a message that's been encrypted or digitally signed and you haven't installed the S/MIME control, you'll see a warning in the message header notifying you that the S/MIME control isn't available. The message will direct you to the S/MIME options page where you can install this control.
  • A digital ID isn't necessary to verify the signatures of digitally signed messages. However, you can't read encrypted mail or digitally signed mail unless you have a digital ID and the S/MIME control is installed. You have to be using Internet Explorer 7 or Internet Explorer 8 on a 32-bit operating system to read encrypted messages and to verify digital signatures.

What if I want to know more?