If you have an email address for a while, you’ll know that “spams” are almost inevitable. Once the email address has been used, spams will find their way there sooner or later. Combating email spams has also become one of the most researched topics these days.

Greylisting is a relatively new method to use against spams, and its principle is very different from traditional content filtering/content classifying strategy. The differences make it very effective in stopping spams currently, utilising relatively little CPU time and has small memory footage. It by no means is a replacement for fiter/classifier based spam protections, but can be easily deployed as first level of defense to reduce the CPU/memory demand of your spam filters.

This article was written after successfully implementing greylisting on Postfix using Gld, on a memory-restrained VPS running Gentoo Linux. Hopefully it will be useful to those who are thinking of implementing a similar solution.

May has been a pretty bad month for Unixshell — no more space in the data centre, and dom0 servers kept on crashing due to some Xen bugs in Linux 2.6.16. However, after Matt and his engineering team fixing up the issues, it has been smooth sailing since.

This is what I get this morning when I logged into my VPS.

I am an Australian, and Australia is a tiny place. Well, the land is big, but majority of 20+ million people chose to squeeze into a few coastal cities. Web hosting is expensive here, and everyone went “wow” when Aussie HQ introduced their million-dollar real time provisioning dedicated server this month (see all the buzz on this Whirlpool thread). I mean, you have enough customers and servers in Australia to provision dedicated servers in real time? Instead of hours or even days of waiting? No wonder they claimed to be Australia’s first.

But it is a dwarf in comparison to Amazon’s Elastic Compute Cloud (EC2), which is currently at limited beta.

Found a great website today that is useful to the webmasters. lookupCrap.com has its tagline “‘Cause there’s crap you gotta lookup”. Yes indeed, that there are lots of craps, bad guys, dodgy companies on the big bad Internet which you need to be very careful of. lookupCrap.com cannot eliminate them, but it gives you an extra hand to work out which ones are dodgy.

Registrar can’t do DNS for you? Need your domain name information hosted? Prefer free lunch? All my domains (around 10+) have been hosted on free DNS servers over the years, and most of them are very reliable. I will be sharing some of these free DNS hosting in this article.

There is an interesting forum post explaining how you can get Gentoo to emerge essential packages on VPSlink’s basic VPS with only 64Mb of memory! I originally thought it would be impossible, but by mangling GCC’s garbage collection parameters it indeed can be done.

GoDaddy.com, the domain registrar company that brought us cheap domains back in earlier part of this century, has recently doubled the storage space and data transfer of its already insanely oversold shared hosting plans. For example, 100Gb storage and 1,000Gb data transfer just costs you $6.99/month, or cheaper if you sign up longer terms.

Disaster happens — even to web hosting companies. You get operating system/software issues, server hardware issues, network glitches and data centre issues and even interrupted electricity that plague your hosting business. Worse, when they all come one after another within a short time span. It is what happened to DreamHost last month, and they are still in the process of picking up the pieces. Many web sites were affected, and outrages were everywhere around the blogosphere.