Supporting RFC2822

By Larry Seltzer  |  Posted 2004-05-03 Print this article Print

The chairmen also say they believe that the framework developed needs to be capable of supporting the needs of an RFC2822 mechanism. I asked Meng Wang Wong, chief architect of SPF, whether it is extensible enough to take on such a job and got an enthusiastic yes. "SPF was designed with things like Caller ID and [Domain Keys] in mind and is extensible to support both of them. No change to the existing specification is needed." He is also continuing efforts to work with Microsoft and Yahoo.

The authors of this new spec will certainly know that its only the beginning, because RFC2821 identities are far from adequate. All a spammer (or worm) needs to do is to use a legitimate envelope address, and the message can come through to the user presenting fraudulent addresses. In other words, 2821-focused solutions dont do anything to address the phishing problem.

What 2821 solutions do allow is the potential for rejecting messages without having to read them first. In other words, if you can determine that the envelope violates policy, you can reject it without actually getting the spam or worm onto your system. Some on the MARID mailing list have challenged the idea that you can do this reliably. Some of the challenges are reasonable, some not, but clearly RFC2821 is not the complete answer.

Of course, if RFC2822 identities were easy and dispositive, there would be a consensus on them, but there isnt. Microsofts Caller ID relies on these identities to address the phishing problem. Lots of people have problems with Caller ID, the specific proposal, not least with the comparative verbosity of the syntax. And there have been credible arguments that there are ways to get around RFC2822 checks.

I spoke to Rand Wacker, director of product strategy at Emeryville, Calif.-based Sendmail Inc. Sendmail is uniquely positioned for this issue, being perhaps the most significant MTA vendor. It has no particular interest in one approach or the other and has been working with developers of all of them to bring working code into the real world, where users can experiment.

Wacker said Sendmail would like to get a variety of approaches out there for real-world testing. Remember, you dont need to support only one; a single site could support multiple standards, and theres reason to. As Wacker points out, IP-based solutions such as SPF and caller ID break mail forwarding.

Even Meng Wang Wong has said on the MARID mailing list that he believes the eventual solution to RFC2822 authentication should involve cryptography, an allusion I assume to Yahoos Domain Keys. Many experts Ive spoken to admire Domain Keys and wish it were more implementable at present. Unfortunately, it faces a number of challenges, including the fact that Yahoo has never really announced it and certainly has no final specification. Theres also a lot of concern that the cryptographic requirements will overburden old mail servers, but Sendmails Wacker said that in the companys work with Domain Keys, the CPU requirements have been reasonable.

All of this leads me to believe that the group is moving far too fast. I agree with Wacker about real-world experimentation. Is it really necessary to have a standard so quickly, when were so early in the real-world implementations of the major proposals? I wish we could wait to get more experience with them first.

Security Center Editor Larry Seltzer has worked in and written about the computer industry since 1983. Check out eWEEK.coms Security Center at for security news, views and analysis.
Be sure to add our security news feed to your RSS newsreader or My Yahoo page: More from Larry Seltzer

Larry Seltzer has been writing software for and English about computers ever since—,much to his own amazement—,he graduated from the University of Pennsylvania in 1983.

He was one of the authors of NPL and NPL-R, fourth-generation languages for microcomputers by the now-defunct DeskTop Software Corporation. (Larry is sad to find absolutely no hits on any of these +products on Google.) His work at Desktop Software included programming the UCSD p-System, a virtual machine-based operating system with portable binaries that pre-dated Java by more than 10 years.

For several years, he wrote corporate software for Mathematica Policy Research (they're still in business!) and Chase Econometrics (not so lucky) before being forcibly thrown into the consulting market. He bummed around the Philadelphia consulting and contract-programming scenes for a year or two before taking a job at NSTL (National Software Testing Labs) developing product tests and managing contract testing for the computer industry, governments and publication.

In 1991 Larry moved to Massachusetts to become Technical Director of PC Week Labs (now eWeek Labs). He moved within Ziff Davis to New York in 1994 to run testing at Windows Sources. In 1995, he became Technical Director for Internet product testing at PC Magazine and stayed there till 1998.

Since then, he has been writing for numerous other publications, including Fortune Small Business, Windows 2000 Magazine (now Windows and .NET Magazine), ZDNet and Sam Whitmore's Media Survey.

Submit a Comment

Loading Comments...
Manage your Newsletters: Login   Register My Newsletters

Rocket Fuel