Help Secure E-Mail Servers

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Published: January 7, 2003

Internet Security and Acceleration (ISA) Server 2000 Feature Pack 1 enhances e-mail server security by:

  • Helping to protect your network from unwanted e-mail.

  • Providing protection for remote Microsoft Outlook users who access Microsoft Exchange Server e-mail messages over untrusted networks without a virtual private network (VPN).

ISA Server Feature Pack 1 also includes enhancements for Outlook Web Access that are detailed in Help Secure Web and Outlook Web Access Servers.

Help Protect Your Network from Unwanted E-Mail

Use the ISA Server application-layer filtering technology to help secure e-mail servers. Scanning e-mail traffic at the network edge reduces the likelihood of viruses and unwanted messages entering the corporate network. ISA Server with Feature Pack 1 can filter out e-mail based on administrator-specified attributes with increased reliability and security.

Enhanced SMTP Filter

The Simple Mail Transfer Protocol (SMTP) application filter intercepts SMTP traffic that arrives on port 25 of the computer running ISA Server. The filter accepts the traffic, inspects it, and passes it on only if the rules allow it. The SMTP filter can filter e-mail based on attachment name, extension, or size, as well as by sender, domain, keyword, or any SMTP command and its length.

SMTP Command Rule dialog box

The SMTP filter can scan e-mail based on many attributes, including any SMTP command and its length.

Provide Protection for Remote Outlook E-Mail Access Without a VPN

ISA Server enables Outlook e-mail communication to servers running Exchange over untrusted networks without setting up a VPN. This capability has been enhanced in ISA Server Feature Pack 1.

Enforce RPC Encryption

ISA Server Feature Pack 1 enables administrators to enforce encryption for all remote procedure call (RPC) communication between Outlook clients and servers running Exchange. This setting enables encrypted communication without setting up a VPN connection. The following diagram illustrates the use of ISA Server Feature Pack 1 with Outlook and Exchange.

Inbound RPC communication diagram

Enable Outbound RPC Communication

With ISA Server Feature Pack 1, Outlook clients protected by ISA Server can communicate with a server running Exchange located outside the firewall. ISA Server Feature Pack 1 enables outbound RPC communication, as shown in the following diagram.

Outbound RPC communication diagram
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