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Q181921: XADM: Sending Encrypted Mail to Users with Different Encryption

Article: Q181921
Product(s): Microsoft Exchange
Version(s): WINDOWS:4.0,5.0,5.5
Operating System(s): 
Keyword(s): kbusage
Last Modified: 02-APR-1999

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The information in this article applies to:

- Microsoft Exchange Server, versions 4.0, 5.0, 5.5 
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SUMMARY
=======

Using the Microsoft Exchange Key Management Server, users have the ability to
encrypt messages. The North American version of the Exchange client can encrypt
messages using a 64-bit encryption key. This level of encryption cannot be
exported out of the United States and Canada; therefore, international Exchange
clients are only enabled with 40-bit encryption.

This article describes what happens when a user with 64-bit encryption tries to
send a messages to other users, some of whom have 64-bit encryption and others
have 40-bit encryption.

MORE INFORMATION
================

The level of encryption that a mailbox is enabled with is stored in the Exchange
directory. When you send a message to a user, it is possible to determine what
level of encryption that user has.

When a user with 64-bit encryption sends an encrypted message to a mixed group of
users with 40-bit encryption and 64-bit encryption, Exchange uses the strongest
encryption level that all recipients have in common. In this case, it selects
40-bit encryption. A 64-bit client can read a message encrypted with a 40-bit
key.

If any one of the recipients is not security-enabled, then the Exchange client
displays a message asking the sender either to send the message without
encryption or to remove the users who are not security-enabled from the list of
recipients.

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Keywords          : kbusage 
Technology        : kbExchangeSearch kbExchange500 kbExchange550 kbExchange400 kbZNotKeyword2
Version           : WINDOWS:4.0,5.0,5.5
Issue type        : kbinfo

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