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Microsoft to beef up SMTP relay for Exchange

As part of its effort to combat spam and viruses, Microsoft announced on Tuesday that it will make improvements to the Simple Mail Transfer Protocol (SMTP) relay for its Exchange messaging platform.

As part of its effort to combat spam and viruses, Microsoft announced on Tuesday that it will make improvements to the Simple Mail Transfer Protocol (SMTP) relay for its Exchange Server messaging platform.

The new capabilities, called Exchange Edge Services, were outlined by Microsoft chairman Bill Gates during a keynote at the RSA Conference in San Francisco. In addition to locking down Exchange, the initiative is designed to make the handling and routing of e-mail traffic more efficient, Microsoft said. The product is slated for release in mid-2005.

"The viability of the e-mail system as we know it is threatened by the constant deluge of information -- both wanted and unwanted -- that companies receive daily and hourly," said Paul Flessner, senior vice president of Microsoft's server platform group, in a statement. "Exchange Edge Services will be a comprehensive way for customers to better protect their Exchange e-mail infrastructure and improve the efficiency of the handling of the tremendous amounts of incoming and outgoing e-mail traffic."

The viability of the e-mail system as we know it is threatened by the constant deluge of information that companies receive daily and hourly.
Paul Flessner
Microsoft senior VP

One industry observer acknowledged Microsoft's effort but said that the technology will not be state-of-the-art network-edge security.

In a report, San Francisco-based Ferris Research Inc. said that, while Exchange Edge Services won't provide all of the functionality of hardware and software SMTP firewalls now on the market, it will be a useful security tool for Windows-exclusive IT organizations that prefer the simplicity of dealing with one vendor.

"Some organizations have a single-supplier strategy," report author Richi Jennings said. "However, our advice would be that, in order to improve security, organizations should implement a heterogeneous mixture of technologies, rather than relying on [a] single vendor."

Jennings, a research analyst at Ferris, described the planned Exchange offering as an SMTP mail transfer agent (MTA) -- or relay -- that implements an SMTP firewall to secure the boundary between an internal enterprise messaging network and the public Internet.

Jennings, however, said that Microsoft isn't breaking any new ground with that capability. "Any MTA can do Internet routing," he said. "This is no big deal."

The product will be built from scratch, and it will not use Active Directory or be embedded in Internet Information Server (IIS), he said.

In the report, Ferris outlined four key functions that Exchange Edge Services is expected to perform:

  • Rejecting SMTP connections from specific IP addresses.
  • Verifying sender addresses. (Microsoft and others describe this as "e-mail Caller ID.")
  • Filtering inbound e-mail traffic for viruses, spam and offensive content.
  • Filtering outbound e-mail traffic for content prohibited by an organization, such as offensive words.

Microsoft said that, as an SMTP relay, Exchange Edge Services will serve as an e-mail gatekeeper when relaying e-mail to and from the Internet. It will also help block junk e-mail by serving as an infrastructure for third-party antispam and antivirus software.

Jennings said that infrastructure will come in the form of a new application programming interface (API) that third-party vendors will be able to leverage for their products.

"They are setting API standards -- this event-driven API -- that allows third parties to plug in antispam, antivirus, content management tools and stuff that we haven't even thought of yet," he said of Microsoft. "Because of their dominant position, that API will allow a rich ecosystem to spring up [among] third-party vendors in content management and other areas."

Microsoft also said that the edge services product will apply basic routing server rules, from relaying and address rewriting to format conversion, and will provide "the basic engine" to allow an administrator to build custom rules.

Jennings said that the announcement of Exchange Edge Services is a public signal by Microsoft that its current message transfer agent technology is lacking in security and availability. But he said that if the product effectively meets its aim, Exchange administrators will have an alternative to the current practice of relying heavily on SMTP products, such as Sendmail, that they know little about. He called that practice "a disaster waiting to happen."

"[Sendmail is] a very capable, very functional product, but the potential disaster comes when people try and get too clever and [go] beyond their capabilities as a Sendmail admin," Jennings said.


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