Guide to the Secure Configuration and Administration of Microsoft ...

Exchange to “Foreign” E-mail System
Jack (Client)
Exchange can also connect to what Microsoft terms “foreign” e-mail systems. Foreign email
systems are simply e-mail networks outside of the Exchange environment, such as
X.400 and Simple Mail Transport Protocol (SMTP) mail systems. Exchange Server 5.0
and Exchange Server 5.5 provide connectors for both of these. Exchange Server 5.5
and third party vendors offer additional connectors that are not covered in this document.
The X.400 connector provides connectivity to X.400 hosts. Server-to-server
communication between Exchange and X.400 hosts is not encrypted, nor is any kind of
robust authentication provided. Only plain text authentication is available as an option.
The Internet Mail Service (IMS) provides connectivity to SMTP hosts. In Exchange
Server 5.0 there are no encryption or authentication options when connecting to non-
Exchange SMTP hosts. In Exchange Server 5.5, Secure Socket Layer (SSL) encryption
and Simple Authentication and Security Layer (SASL) authentication can be used
provided these features are supported by the other hosts with which the Exchange
Server will connect. Please note that this feature is not well documented and attempts
by the author and others to enable SMTP over SSL have failed.
GWS1 (Server)
VulCo
(Organization )
Washington (Site)
Baltimore (Site)
GWS2 (Server)
Authentication:
-X.400: Simple, non-encrypted
passwords
-Internet Mail Service: SASL optional
(Exchange 5.5)
Encryption:
-X.400: None
-Internet Mail Service: SSL optional
(Exchange 5.5)
Foreign E-mail Networks
Figure 3 Exchange to “Foreign” E-mail Systems -- Security Options
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