Thansk to all who replied to the original thread. I finally managed to build the
RPMs for Courier. I had to modify the spec file for this, so I had to use:

Rpmbuild -ba rpm/SPECS/courier.spec (not rpmbuild -ta zipfile)

Changes needed in the spec file:

1 override the fax stuff with '$define with_fax 0'

2 Do NOT stop on unpackaged files $define_unpacked_files_terminate_build = 0

3 Tell configure NOT to use caching by changing the './configure' line to: --cache-file=/dev/null

4 Tell configure to look for the mime.types file in /etc/cups: --enable-mime=/etc/cups/mime.types

Re 1/2: still fax related files are installed but not packaged up. They should
not be instlled in the first place... For some strange reason the netpbm libs are NOWHERE to be found (for Mandriva).
Is this obsolete stuff or whatever? Alas, I was not going to use fax.

Re 3: the cache mechanism in configure is broken as far as I'm concerned.
Checking all kind of options that *should* not change is fine but PLEASE make it
collapse multiple spaces into single space before comparing old and new. It
errors out on the fact that '-O2 -pipe' is different than '-O2 -pipe'.

Re 4: On my system (Mandriva 2006.0) the only mime.types file I could find was
in /etc/cups.

Hope this helps others too!