I was trying to install netatalk-2.0.3 so I could use AFP on my Ubuntu box with Mac OS X Tiger. Unfortunately, I was getting this error message.
The steps for getting netatalk:
mkdir -p ~/src/netatalk
cd ~/src/netatalk
sudo aptitude install devscripts cracklib2-dev dpkg-dev libssl-dev
apt-get source netatalk
sudo apt-get build-dep netatalk
cd netatalk-2.0.3
DEB_BUILD_OPTIONS=ssl sudo dpkg-buildpackage -us -uc
sudo debi
What wasn’t working:
:~/src/netatalk$ apt-get source [...]

Synaptic is a package manager in Ubuntu which makes it really easy to install applications. I wanted to find out how to install Synaptic on Ubuntu Server 6.06 LTS, and here’s what I found. It worked for me, so hopefully this helps you, too.
Install Synaptic (source):
apt-get install synaptic gnome-system-tools file-roller
Stop gdm from starting automatically (useful [...]

Here’s the trick:
apt-get install postfix libsasl2 sasl2-bin libsasl2-modules libdb3-util procmail
Got it from here. I chose Internet Site as my configuration option. I was afraid this would require further configuration to work with PHP, but it’s actually working fine, so I’m really happy.

I could’ve saved so much time today if only I’d known some things. There are many Ubuntu/Linux related things that are just way too hard to do, and way too difficult to find on the web, even with Google. Here’s one gem to fix the problem in the title:
1: Start Synaptic: System->Administration->Synaptic Package Manager
2: Add [...]