With RPM 4.2.1, "mozilla = 1.2.1-26" means mozilla 1.2.1-26 with epoch 0. With RPM 4.2, "mozilla = 1.2.1-26" means mozilla 1.2.1-26 with any epoch.
I recall xmms had similar packaging bugs back then...
The new (4.2.1) behavior is more predictable, but it breaks backward compatibility with old packages that have broken requirements specifications (i.e., missing specific epochs when they're needed). If we want to move Red Hat 8.0 and 9 over to the new behavior, we could make new mozilla, etc. packages that work properly with RPM 4.2.1, however.
Updates for Mozilla will most likely be needed one day, because of the very large complexity of a behemoth like Mozilla we will surely have a security update in the future. I think.
Warren