Browsing in her local card shop, a woman went home with what she thought was a big bargin -- a dozen boxes of small-sized notes and party invitations, all on sale.

But after July 15, she won't be able to mail them. That's when the U.S. Postal Service puts into effect its ban on small-sized pieces of mail, including undersized social notes and minisize postcards. [Some retailers still have undersized writing paper they are trying to sell out before the new standards become effective.]

The new regulations will ban pieces of mail less than 3 1/2 inches high, and 5 inches long, or .007 of an inch thick, according to Van Seagraves, information officer of the U.S. Postal Service.

Small pieces and flimsy cards become trapped in other mail and tear and jam the processing machinery, he said.

Any pieces found smaller than the new minimum measurements will be returned to the sender. Small computer-punch cards, for example, should be enveloped.

Exceptions to the ban include film mailers, tiny boxes hotel keys, identification cards and tags which are more than 1/4 of an inch thick. These pieces can be culled mechanically from the "river" of letter mail moving through the equipment.

The new regulations have been on the drawing boards for three years, giving manufacturers of undersized envelopes time to adjust their stock.

The new regulation have been on the drawing boards for three years, giving manufactures of undersized envelopes times to adjust their stocks.

Also on July 15, oversized and oddshaped pieces of mail, such as large greeting cards, will have a 7-cent surcharge, said Seagraves. The surcharge will be added only to oversized and odd-shaped first-class mail of 2 ounces or less that exceed any of these dimensions -- 6 1/8 inches high, 11 1/2 inches long and 1/4 of an inch thick. CAPTION: Picture, no caption