Require 128-Bit Encryption
The key pairs you configure for TLS encryption consist of a number of bits that indicate the key's security level. You can strengthen security by increasing the encryption level from 40 bits (the default) to 128 bits. The greater the number of bits, the more difficult the item is to decrypt.
Important Users attempting to access this virtual server must use the same encryption level that you set, or messages will be returned with a non-delivery receipt (NDR).
Note Due to export restrictions, the 128-bit key strength encryption feature may not be available in all countries. For information about upgrading to 128-bit encryption capability, see http://support.microsoft.com/support/.
To require 128-bit encryption levels for the virtual server: