D. J. Bernstein
Internet surveys

Bogus popularity claims for Sendmail

``Sendmail currently processes more than three-quarters of Internet correspondence,'' the news reports say. What, you ask, does this statistic mean? How exactly was it measured?

Here's the real story.

1996: I surveyed the Internet's reachable SMTP servers, and found that 80% were running Sendmail.

1997: I did it again: 76% Sendmail.

March 1998: Sendmail Inc. announced the commercialization of Sendmail. It proudly pointed to my surveys, with a link straight from their web pages to mine, and stated that more than 75% of the Internet's SMTP servers were running Sendmail.

Newspapers don't want to use technical words such as ``SMTP'' and ``servers,'' so typical news reports about Sendmail Inc. said that Sendmail ``routes an estimated 75 percent of email on the Internet.'' But that was a completely unreasonable estimate. SMTP surveys count an idle workstation just as heavily as a busy mail server like mta1.onelist.com or mx1.pair.com; Sendmail is much less popular on busy mail servers than it is on idle workstations.

May 1998: My *.net mail exchanger survey showed only 63% Sendmail. Sendmail Inc. removed their link to my web pages. They continued to claim prominently on their web pages that Sendmail was ``installed on over 75% of Internet mail servers world-wide.''

Late 1999: A typical Sendmail Inc. press release said that Sendmail installations were ``over 75 percent of all Internet mail servers.'' Meanwhile, newspapers continued misrepresenting ``percent of all Internet mail servers'' as ``percent of all Internet mail.'' The sendmail.net web pages, ``sponsored entirely by Sendmail, Inc.,'' stated that Sendmail ``handles an estimated 75 percent of the Internet's email traffic.''

April 2000: I surveyed the *.com mail exchangers and the Internet as a whole, demonstrating conclusively that Sendmail was no longer installed on 75% of Internet mail servers. Sendmail changed its web pages to say that Sendmail ``powers the majority of the Internet's mail servers.'' It didn't fix the sendmail.net web pages.

October 2000: My latest survey showed that Sendmail had dropped below 50%.

November 2000: ``The open-source Sendmail is a mail transfer agent used to move 75% to 80% of the e-mail on Simple Mail Transfer Protocol (SMTP) servers worldwide, according to a 1998 study at the University of Chicago,'' a typical news story said. ``Sendmail ... is the de facto implementation standard for SMTP and the related protocols that define e-mail transfer on the Internet.''

May 2001: The Sendmail web pages said that ``Sendmail routing software is the de facto SMTP implementation and dependably powers the vast majority of the Internet's mail servers today.''

September 2001: The Sendmail web pages still said that Sendmail ``powers the majority of the Internet's mail servers.'' The sendmail.net web pages still said that Sendmail ``handles an estimated 75 percent of the Internet's email traffic.''

October 2001: My latest survey showed Sendmail continuing to drop in popularity.

March 2003: Typical news reports of the latest Sendmail remote-root bug claimed that ``between 50 and 75 percent of all the Internet's e-mail is handled by the various versions of Sendmail.''