no time to check, but i think the file should be there, or posfix will give error.But, it would probably be useful to have header_checks = regexp:/etc/postfix/header_checks enabled in the default postfix config, users who don't use it won't see the difference, and users who do will want it.
It might also be an idea to supply good sample header_checks (ie header_checks_windows_executables or something).
yes, that could be a good idea.
Also, how about including a transport in master.cf for amavisd-new, then %post of amavisd-new could postconf itself as a content_filter, and it would work out-the-box.
with amavis we should also split the cleanup service in two entries and create the backdoor smtp server, and i don't think those belong in the default config. (unless we decide to ship antivirus/antispam in the default config, wich at this particular time could prove a good marketing move for mandrake).
regards, L.