OLEXP: Outlook Express Does Not Send 128 -Bit Encrypted E-mail Messages by Using Digital IDs

If you download a Digital ID from or confirmed through a Lightweight Directory Access Protocol (LDAP) server, Outlook Express does not use 128-bit encryption when sending an e-mail message by using this Digital ID.

If the Warn on encrypting messages with less than this strength security setting is set to 128 bit or more, you receive the following message:

This issue is by design following the Secure/Multipurpose Internet Mail Extensions 2 (S/MIME2) specification. There are many e-mail clients that do not support Secure/Multipurpose Internet Mail Extensions 3 (S/MIME3), so the S/MIME2 default (RC2 40-bit) is used for encryption when Outlook Express does not know the capabilities of the recipient.

For information about the S/MIME version 2 specification, please see section 2.6.2.4 of RFC 2311, "S/MIME Version 2 Message Specification." RFCs are available at the following Internet Engineering Task Force (IETF) Web site: Microsoft provides third-party contact information to help you find technical support. This contact information may change without notice. Microsoft does not guarantee the accuracy of this third-party contact information.