If there is a problem with control/badloadertypes, qmail-badloadertypes complains and leaves control/badloadertypes.cdb alone.
qmail-badloadertypes ensures that SQMAIL/control/badloadertypes.cdb is updated atomically, so qmail-smtpd never has to wait for qmail-badloadertypes to finish. However, qmail-badloadertypes makes no attempt to protect against two simultaneous updates of control/badloadertypes.cdb. For convenience, qmail-badloadertypes allows comments (lines starting with '#') and copies only the significant leading characters to control/badloadertypes.cdb.
The binary control/badloadertypes.cdb format is portable across machines.