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

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.

Roosevelt's magic lay in one facet of his personality: He knew how to take the risk. No other man in public life I knew could so readily take the challenge of the new.

To do the Ozzfest again would be great. I'd like to finish with a final Sabbath album. You always feel that it is still a challenge.

People are not perfect... very often the relationships that are strongest are those where people have worked through big crises, but they've had to work through them. So the challenge to us is to work through that.

Every single book is a challenge.

Critics are sentinels in the grand army of letters, stationed at the corners of newspapers and reviews, to challenge every new author.

The lopsided attitudes of college professors pose a serious challenge to learning because students are so susceptible to becoming lopsided sheep.

I really enjoy comedy. It's a real challenge.

I had a hard time with that hockey. I hadn't grown up skating, so that was my biggest challenge. We worked on it and worked on it. But then when we first shot it, it was so hard for me.

The challenge is to practice politics as the art of making what appears to be impossible, possible.

Change can either challenge or threaten us. Your beliefs pave your way to success or block you.

My greatest challenge has been to change the mindset of people. Mindsets play strange tricks on us. We see things the way our minds have instructed our eyes to see.

I'd say that it's important for music to be there that gives you a challenge, that rearranges things in your head.

I like good stories. Quality products and character are what's important. Even if the script isn't that strong, if I challenge myself with a great character, I'll go for it.

I tend to arrive in the rehearsal process with very strongly developed ideas about what I want to do. But I don't like those ideas to be things that are not subject to change, or subject to development, or subject to challenge.

I'm not looking to set a standard... but, I believe I have offered a challenge to others with my work.

If you live a life of make-believe, your life isn't worth anything until you do something that does challenge your reality. And to me, sailing the open ocean is a real challenge, because it's life or death.

And, I'd never done Tennessee Williams, and I had done Broadway musicals, so it was a challenge.

When you remove the risk, you remove the challenge. When you remove the challenge, you wither on the vine.

After Land I wanted to continue exploring the theme but I needed a new challenge so turned to colour. I explored Bradford and produced a series of urban landscapes that I liked, but because Land had made such an impact on the general public my colour work wasn't reviewed.

The worlds I paint leave a lot to engage the imagination by hinting at what lies beyond the four edges of the painting. I think getting beyond the four edges of an opportunity or challenge is one of the basic skills you need in business.

For me, it's a bigger challenge, it's much harder to do and much more rewarding to do well, then just to think up stuff of your own, hit or miss, because you've got to see to it that you don't torpedo any of his punch lines.

This same habitual blindness to spiritual, substantive dimensions of every significant challenge continues to handicap Hollywood.

Every artist has to grow, and has to challenge themselves with a new form of expression.