Once the stamps hit the mass market in 1994 there was a new problem: they quickly became so popular that post offices could not keep up with the demand.

If there were complaints this time, it was that the Postal Service did not shift quickly enough to the self-adhesive newcomers, which are much easier and faster and more sanitary to use.

Other objections came from environmentalists and recyclers. They complained that the glue on the self-adhesive stamps, because it was not soluble in water, created blemishes and holes in recycled paper.

But the Postal Service said that the problems were relatively minor and that an ''environmentally benign'' glue for self-adhesives was within sight, needing just a bit more testing. The postal powers, seeking even higher environmental virtue, have also begun issuing ''linerless'' rolls of self-adhesive stamps, which unroll like Scotch tape and save on waste because they need no backing.

That leaves only some stamp collectors unhappy. They have long complained about the self-adhesive stamps because they did not lend themselves to the hobbyists' need to tear off one stamp for placement in an album.

But lately, self-adhesives have become better even for collectors, said William Crowe, a senior expert at the Philatelic Foundation in New York. The latest sheets of the Bugs Bunny stamp, he said, have been issued in a perforated format that makes it easier to take off one stamp.

Mr. Crowe surmised that gummed stamps would stay around for quite a while, though, because they are better suited for packages that require several stamps at once. ''In the good old days, you'd lick the whole back of a block of 12 and it went on very easily,'' he said.