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.

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.

We used to think that revolutions are the cause of change. Actually it is the other way around: change prepares the ground for revolution.

I must stress here the point that I appreciate clarity, order, meaning, structure, rationality: they are necessary to whatever provisional stability we have, and they can be the agents of gradual and successful change.

Excuses change nothing, but make everyone feel better.

So, first you have to be able to play with a metronome. Then you take your freedom. If you play in an orchestra, you got to watch the conductor, he is like a metronome, but it is more difficult because he can change rhythms.

I wouldn't change Buffy for anything and I wouldn't change the course in which she has evolved but it is nice to be able to do something that is a little different.

For example, UNICEF works with governments to change legislation such as in India where a law was passed raising the age of compulsory school completion to keep children in school and away from the workplace for longer.

Great joy, especially after a sudden change of circumstances, is apt to be silent, and dwells rather in the heart than on the tongue.

I still feel that a movie has to attempt to say something - even if it fails miserably. But I've sort of given up on believing that I'm going to change the world with every film I choose to act in.

Don't knock the weather; nine-tenths of the people couldn't start a conversation if it didn't change once in a while.

You don't have to be the Dalai Lama to tell people that life's about change.

I knew that my staying up would not change the election result if I were defeated, while if elected I had a hard day ahead of me. So I thought a night's rest was best in any event.

It will always be a battle a day between those who want maximum change and those who want to maintain the status quo.

Being a father, well, I don't know if this is a change, but it makes me want to get out of here faster. Get off the clock. Just 'cause the baby is my reason for living, my reason for coming to work.

A liberal knows that the only certainty in this life is change but believes that the change can be directed toward a constructive end.

I was born not knowing and have had only a little time to change that here and there.

In their search for quality, people seem to be looking for permanency in a time of change.

The game has kept faith with the public, maintaining its old admission price for nearly thirty years while other forms of entertainment have doubled and tripled in price. And it will probably never change.

One day I actually took the list into the bathroom and I put it up against my face and looked in the mirror and I realized I had one of two choices, change the list or change myself.

But the real focus should be on people who are buying today because the base is so big it will take a long time for any change materialize on an overall basis.

Markets change, tastes change, so the companies and the individuals who choose to compete in those markets must change.

The psychological basis of the metropolitan type of individuality consists in the intensification of nervous stimulation which results from the swift and uninterrupted change of outer and inner stimuli.

Headteachers and governing bodies run schools and that won't change.

Using the power of decision gives you the capacity to get past any excuse to change any and every part of your life in an instant.