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A Talk with the Father of sendmail

A Talk with the Father of sendmail

LWM: It wouldn't be overstating the case to call you a living legend. How does it feel to be the creator of one of the most used pieces of software on the Internet?
Eric Allman: I sure don't feel like a legend. I have to remind myself sometimes that I haven't taken the typical career path - it's always seemed very natural to me. Mostly I've worked on what seemed interesting at the time, and that's served me well. Of course, luck had a lot to do with it too.

LWM: Many new technologies have emerged, but still one of the most used communication channels is good old trusted e-mail. What would you attribute this success to?
Eric Allman: E-mail fits the needs well. It has immediacy without being demanding (the telephone needs to be picked up right now). There will always be a place for voice mail and instant messaging of course, and to a certain extent IM will replace some use of e-mail, just as e-mail replaced some use of fax and fax replaced some use of postal mail. But none of those technologies went away - far from it.

E-mail is also complementary to a lot of these other technologies, and in some cases may even enhance them. For example, as IP telephony emerges I expect to see at least some revival of voice mail - but transmitted via e-mail.

LWM: sendmail is one of those great pieces of software that you can literally forget about as it "just works." What's your secret?
Eric Allman: Before I did sendmail, I worked on the INGRES project at Berkeley. INGRES was one of the first Relational Database Management Systems (the other was System R, which evolved into DB2). A lot of the emphasis in DBMS is reliability, recovery, etc., which requires a certain way of thinking about the problem. So I guess it all comes down to "good engineering" - anyone can do it if they are obsessive enough.

LWM: Software goes through many evolutions in its lifetime. With sendmail over 20 years old now, what are the 3 most significant stages sendmail has gone through?
Eric Allman: The first version of sendmail was actually called delivermail. This was pre-Internet and depended heavily on all the other mail subsystems (UUCP, Berknet, etc.) having their own queuing. The transition from there to sendmail, which included adding queuing and Internet support, was major.

The second big transition was between sendmail 5 and sendmail 8, which pulled in a lot of ideas that had been added into other versions of sendmail. It was a conscious attempt to remerge the various code lines and modularize a lot of the internals. This transition also added the M4-based configuration system that sendmail has today.

I'm not sure there has been a third major transition yet, but there have been some significant jumps that occured over time. I'm a big believer in making many small changes instead of a few large ones when you can. For example, the sendmail 5 to sendmail 8 transition involved a fair amount of modularization in the code, but that continues to happen from version to version. So in a lot of ways sendmail has evolved more than made revolutionary changes.

LWM: With the advent of MIME, you can pretty much send anything using e-mail. Do you think we'll still be discussing e-mail, as we know it now, in another 20 years?
Eric Allman: Yes, probably. But the public might not recognize it as such. I'm using a PowerBook right now to type this, and it doesn't look much like the PDP-11 where the first versions of sendmail were developed. But despite the addition of a graphic display, a mouse, networking, larger disks, lower power consumption, and lots and lots of software, it's still a von Neumann stored program architecture. After all, the holographic messages you see in futuristic science fiction flicks are probably running on SMTP.

LWM: Do you think the SMTP protocol should get a major overhaul to combat the new challenges of today's Internet, such as spam and overly large e-mail attachments?
Eric Allman: That sounds like a trick question. I have to say yes, but no. I believe we need to evolve SMTP, but I'm not wild about throwing it out and starting over. Fortunately, the ESMTP structure permits extensions, so I think making the changes we will need is possible without switching to a major new framework.

I also think an evolutionary approach is essential to avoid having a commercial entity try to "privatize" e-mail protocols. I think that would lead us back to the bad old days of a fractured network, which is what sendmail was trying to address in the first place.

LWM: You are involved with Sendmail, Inc., a commericial venture to support sendmail. What challenges are you facing in providing support for an open source product?
Eric Allman: Depending on how you look at it, either a lot or not much at all. We certainly have some instances where people prefer to run open source rather than commercial, and I view that as just fine, although some of our salespeople might not always agree. But the open source gives us market awareness and reputation that just can't be bought.

The biggest challenges we have right now are the same as any company has these days: a sluggish economy. Fortunately, e-mail isn't one of those trendy things that companies can put off until things improve. Instead, in bad times companies look hard at finding a better, cheaper way of doing things, and standards-based mail tends to be less expensive than proprietary systems.

LWM: It is reported that around 70% of total e-mail transmitted comes in contact with a sendmail gateway at some point in its journey. A significant penentration by anyone's standards. Do you think this has to do with the fact that sendmail was primarily an open source project or that it was adopted by many of the Unix variants as the preferred mail router? Maybe both?
Eric Allman: Definitely both. There was certainly a cause-and-effect relationship between the two as well. But it's also important that, as you noted earlier, sendmail does pretty much "just work" - even if you may not be wild about the configuration language (I'm not at this point). Without that basic reliability people would have moved off it years ago.

LWM: sendmail has benefited from the explosive growth in Linux over the past decade. How has this changed what you are doing at Sendmail, Inc.?
Eric Allman: sendmail has always been written to be extremely portable, so from the point of view of the code base, not much has changed at all. But from the commercial point of view, it's a major thing. Linux is a Tier 1 platform for us, and that's significant at a small company. Linux is a major player in the server world, especially for companies that are extremely cost-conscious. Linux has been a major driver in our partnerships with HP and IBM, for example.

LWM: What is the most common support call you've seen with sendmail? What are the top "gotchas" for most people?
Eric Allman: The top gotchas? When they don't read the documentation, definitely. Seriously, the vast majority of questions are pretty simple ones that are answered in the documentation, such as how you do masquerading, but that's going to be true on any product. But there are also a lot of nonobvious questions that pretty much run the gamut. People do an immense amount of interesting things with sendmail.

LWM: Are you seeing a shift in attitude from the Fortune 500 toward embracing open source technologies, such as sendmail, Apache, and Linux?
Eric Allman: Without a doubt. Not surprisingly, a lot of this results from vendors that they've already heard of (notably IBM and HP) throwing their weight behind open source, but a lot has to do with cost consciousness and an increasing faith in Linux. Frankly, five years ago I didn't think Linux was really ready for prime time outside of a deeply technical shop. That's changed a lot.

LWM: Let's spool back some 15 years ago - sendmail would have been roughly 5 years old. What was your outlook for the future back then? Did you see sendmail having a limited shelf life?
Eric Allman: I didn't expect it would last this long, although it wasn't anything particularly to do with sendmail per se. Not much software lasts that long (10 years is a good life span), and I figured it would have had a more ordinary life cycle. And honestly, if sendmail had just sat on the shelf it would have died a long time ago - bit rot sets in all by itself.

Look at the sorts of code that have thrived over a long period of time, for example Unix in all of its derivatives. There has been a huge amount of work done on such code. There has been a direct progression from 6th Edition UNIX (the first kernel I hacked on) to FreeBSD, but there isn't much in FreeBSD that resembles that predecessor. Similarly, although I can show you code that I wrote for delivermail that is still in sendmail 8.12, there isn't much of it.

LWM: When you go onsite to a see customer, what makes you have a wry smirk? And conversely, what makes you throw your hands up in horror?
Eric Allman: For the smirk, probably that only the techies know who I am. I had one case several years ago where a vendor rep came in and told me all about sendmail (getting much of it wrong) without even realizing who I was. I enjoyed letting him chew on his foot for a while. That has changed some since I started Sendmail. Now I get invited to speak at economics conferences, albeit about open source in general, not sendmail in particular. And it's just cool to see how they rely on this body of code I wrote. It's the ultimate in ego strokes when people actually use your stuff - speaking as someone who was raised in academia where success is often claimed because a couple of hundred people read your paper.

As for throwing up my hands in horror, let me count the ways.... I think prudence suggests that I shouldn't be too explicit about the amazingly stupid things that people try to do. Use your imagination.

LWM: People and organizations alike are paranoid about security. Should they be?
Eric Allman: Arguably, not paranoid enough. Or more precisely, they care too much about things that aren't all that important and not enough about the things that are important.

Some pet examples of mine from both the physical and cyber worlds: firewalls are trusted far too much, in that they are sometimes used as an excuse for having inadequate security inside the firewall. "Hard and crunchy on the outside, soft and chewy on the inside" is the way I've sometimes heard it described. On the other hand, people sometimes worry too much about obscure points of cryptography that aren't going to make much difference in the typical (nonmilitary) world. In the physical world, we aren't anywhere near as worried as we should be about people stealing our mail from the end of the front path; identity theft is a serious and under-appreciated problem.

LWM: To your knowledge, what is the biggest installation you know that sendmail is currently deployed in?
Eric Allman: I couldn't even guess. Most of the Fortune 500 run sendmail at least somewhere, although the largest would probably be an ISP somewhere. But ISPs often don't like to talk about the details of their technologies. LinuxWorld Magazine www.LinuxWorld.com

About Eric Allman
Eric Allman is Sendmail, Inc.'s chief technology officer and cofounder. Eric authored sendmail, the world's first Internet Mail program, in 1981 while at the University of California at Berkeley.

The History of sendmail
- 1979 - Eric Allman releases delivermail, delivermail uses FTP to transmit e-mail on the ARPANET, delivermail ships with BSD

- 1981 - Allman changes the name to sendmail after Bill Joy notes he doesn't like delivermail

- 1982 - ARPANET moves to TCP/IP, SMTP Protocol (RFC821) introduced for moving mail around

- 1993 - sendmail releases 8.0 with m4 configuration

- 1998 - Allman & Greg Olson announce formation of Sendmail, Inc.

- 2003 - sendmail installed on approximately 80% of all mail servers

More Stories By Alan Williamson

Alan Williamson is widely recognized as an early expert on Cloud Computing, he is Co-Founder of aw2.0 Ltd, a software company specializing in deploying software solutions within Cloud networks. Alan is a Sun Java Champion and creator of OpenBlueDragon (an open source Java CFML runtime engine). With many books, articles and speaking engagements under his belt, Alan likes to talk passionately about what can be done TODAY and not get caught up in the marketing hype of TOMORROW. Follow his blog, http://alan.blog-city.com/ or e-mail him at cloud(at)alanwilliamson.org.

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