There are many areas of Outlook that are potential problems for administrators. Once such area is the sending and receiving of digitally signed messages.

Digitally signing email messages is a form of protection that can be used to prevent identity fraud and the abuse of email messages sent to and from Outlook. Outlook allows email messages to be sent with cryptographic features such as S/MIME digital signatures and encryption.

Such messages can utilize “public key/private key” encryption technology to make private their email messages so that only recipients who possess a public key are able to view the encrypted email message. There is a complicated mathematical relationship between the two keys such that any message encrypted with the public key can only be decrypted using the specific private key. The reverse relationship is also true: any message encrypted with the private key can only be decrypted using the corresponding public key. It is this reverse relationship which supports digital signatures.

Oftentimes you will run across the situation where an end user complains to you that they cannot open a digitally signed message. When they attempt to do so they receive the following warning message: “Signature not trusted.” This is usually an indication that their email system has not implemented email security yet.

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