I have qmail RPM installed, with explicit Conflicts: sendmail and with at least two conflicting files (/usr/bin/mailq and /usr/sbin/sendmail), no sendmail installed, and in spite of all the above the sendmail gets installed during the system upgrade. I wonder what else can the upgrade process destroy, what would survive the rpm -Fvh * successfuly otherwise. The bug #10382 and this one makes me wonder whether it is safe to use the upgrade using the boot floppy or CD instead of rpm -Fvh /cdrom/RedHat/RPMS/*rpm (with possibly adjusting the problems by hand). I have verified that rpm -Uvh sendmail-8.9.3-20.i386.rpm refuses to install sendmail with "conflicts: qmail-1.03-7" message.
*** This bug has been marked as a duplicate of 6253 ***