One bug in an SMTP server can open up the whole machine for intrusion.

Defect-free software does not exist.

I was going to visit IBM for six months as a visiting scientist. Now, six months is a lot of time, so I came with a whole list of projects that I might want to work on.

I don't expect an overnight change of all desktops to what the US Military used to call B3 level security. And even that would not stop users from shooting themselves into the foot.

However, writing software without defects is not sufficient. In my experience, it is at least as difficult to write software that is safe - that is, software that behaves reasonably under adverse conditions.

I want to avoid locking people into solutions that work only with Postfix. People should have a choice in what software they want to use with Postfix, be it anti-virus or otherwise.

Qmail out of the box works fine, so people will want to use it regardless of licensing restrictions, even when the software does not ship with their system software.

When I write software, I know that it will fail, either due to my own mistake, or due to some other cause.

The challenge with Postfix, or with any piece of software, is to update software without introducing problems.

Sure, but competition is good for the user.

As of today, the Postfix mail transport agent has almost 50,000 lines of code, comments not included.

Like all software, Qmail can survive only when it keeps up with changing requirements.

Most of the effort in the software business goes into the maintenance of code that already exists.

Coming back to the topic of computer security, the TCP Wrapper is an example of such a safety net. I wrote it when my systems were under attack by someone who appeared to walk through walls.

This will surprise some of your readers, but my primary interest is not with computer security. I am primarily interested in writing software that works as intended.

For many people my software is something that you install and forget. I like to keep it that way.

At the time the Sendmail program had a very poor reputation with respect to security, with four root vulnerabilities per year for two successive years.

One bug in an SMTP server can open up the whole machine for intrusion.

Windows favors multi-threading, which means that a service is implemented by one single process.

Writing software that's safe even in the presence of bugs makes the challenge even more interesting.

Postfix keeps running even if one Postfix process dies; Windows requires that someone restarts the service.

Lack of documentation is becoming a problem for acceptance.

The Postfix security model is based on keeping software simple and stupid.

In a previous life I wrote the software that controlled my physics experiments. That software had to deal with all kinds of possible failures in equipment. That is probably where I learned to rely on multiple safety nets inside and around my systems.

My reply is: the software has no known bugs, therefore it has not been updated.

Adding functionality is not just a matter of adding code.

Before you can hit the jackpot, you have to put a coin in the machine.

The typewriting machine, when played with expression, is no more annoying than the piano when played by a sister or near relation.

The genius of the economic machine is in its ability to convert these indulgences into profitability. It converts desire into attention, a grip on our eyeballs and eardrums, which in turn can be marketed to advertisers.

If you put garbage in a computer nothing comes out but garbage. But this garbage, having passed through a very expensive machine, is somehow ennobled and none dare criticize it.

I was about 11 when my mother brought me this karaoke machine and I was really into it back then, but about 4 or 5 years ago is when I started printing up my own music, going to the studio and doing my own thing.

Man is a fire-stealing animal, and we can't help building machines and machine intelligences, even if, from time to time, we use them not only to outsmart ourselves but to bring us right up to the doorstep of Doom.

When the machine had been fastened with a wire to the track, so that it could not start until released by the operator, and the motor had been run to make sure that it was in condition, we tossed a coin to decide who should have the first trial. Wilbur won.

Since, however, it is immaterial whether the work is done by assistants or a machine, I decided to build a machine equivalent to an array of about 200 separating funnels.

Man is a beautiful machine that works very badly.

What that means initially is that you have alot of products that are only slightly better games in the same genre on another machine - and the titles that really take advantage of the machine come along later.

To one who believes that really good industrial conditions are the hope for a machine civilization, nothing is more heartening than to watch conference methods and education replacing police methods.

One of the things I particularly enjoyed doing was taking raw sound from locations during the film, like the candy machine, and writing pieces of music to go with them, which is totally unnecessary within the context of the film, because they have their own logic.

Most countries are static, and they need to do is keep having babies. But America's like this big old clanking smoking machine that just lumbers across the landscape scooping up and eating everything in sight.

Come to think of it, the way I play is like a drum machine- very mechanical.

It was like falling off a building and suddenly, bang, you hit the bottom. The first time it happened was on an ordinary day at home. I was taking down some curtains. I took one step, turned around, took another step and then I fell and hit my head hard on the rowing machine.

Admiration of the proletariat, like that of dams, power stations, and aeroplanes, is part of the ideology of the machine age.

Television is the triumph of machine over people.

I even believe in helping an employer function more productively. For then, we will have a claim to higher wages, shorter hours, and greater participation in the benefits of running a smooth industrial machine.

And when the time comes to replace the O2 I have today, maybe my next machine will run Linux.

I'd watch my father get up at 5 o'clock and go down to the Eastern Market in Detroit to do the shopping for his restaurant, and get that business going and then go out on his vending machine business.

The world changed from having the determinism of a clock to having the contingency of a pinball machine.

Of all human inventions the organization, a machine constructed of people performing interdependent functions, is the most powerful.

Vigorous writing is concise. A sentence should contain no unnecessary words, a paragraph no unnecessary sentences, for the same reason that a drawing should have no unnecessary lines and a machine no unnecessary parts.