Upgrade Operating System
The best advise is to follow the excellent docs at http://www.freebsd.org/handbook/ Follow the directions for updating. There are more specific instructions for upgrading from FreeBSD 4. A few things to help you along are:
toaster_setup.pl -s sources toaster_setup.pl -s ports
That will update your FreeBSD sources and ports tree with the latest versions. Then upgrade FreeBSD using freebsd-update if possible. If not, upgrade from sources as follows:
cd /usr/src make buildworld make kernel mergemaster -p reboot cd /usr/src make installworld mergemaster reboot
The process will vary based on the version of FreeBSD you are upgrading from and to. The above assumes that I have also configured /etc/make.conf. It is best to read the docs first, including /usr/src/UPDATING. Failure to do so can be quite difficult to recover from. If you are upgrading from FreeBSD 4.x to 5.x, be extra careful to follow the instructions exactly.
Upgrade your ports
After upgrading major OS versions, upgrade all the installed ports. I do so like this:
toaster_setup.pl -s ports
This step uses portsnap to download and update your ports tree.
Be very careful when upgrading ports that are manually installed by the toaster, such as qmail, vpopmail, and ucspi, etc. You have been warned. If you let portmaster reinstall qmail and your settings get wiped out, you have yourself to blame.
Finally, it is always a good idea to read /usr/ports/UPDATING before upgrading ports. The ports team is very good about documenting changes that affect a given port. If you read it before upgrading your Mail::Toaster, you will have a pretty good idea why certain things behaves differently after the upgrade, and a better idea of how to fix it.