Hanging their hats on the "green" movement while offering retailers new ways to electronically send ads and coupons to customers, some young companies are pushing "paperless receipt" technology as the next big thing in point-of-sale efficiency. When we recently heard of one such startup, an Atlanta company called Transaction Tree, whose products allow retailers to offer E-mailed receipts instead of receipts printed on paper, we wondered how that would work. Who hasn't been the victim of lost, sent-to-the-wrong-address or spam-bucket-swallowed E-mails? Transaction Tree's answer is to wean people and retailers into trusting its technology. First-time users of the company's E-mail receipt system will be issued "tiny, little receipts" by the cashier, said Transaction Tree Chief Operating Officer and Co-Founder Jose Jimenez. These won't really be receipts, he noted, just slivers of paper that include three vital pieces of data: the Web address of Transaction Tree's online portal, the E-mail address that was input by the cashier (or by the customer) at the time of sale and a transaction number. Immediately after the sale, the customer can check the paper stubs to see if the E-mail address is correct. Customers can also go to the Transaction Tree Web portal and (unless they're really unlucky) find a record of the sale. Jiminez stressed the stub is issued only the first time a customer uses Transaction Tree at the POS, primarily to prove the system works. Another new company pushing paperless receipts is allElectronic. Company Co-Founder and CEO Isaac Lay said his business cuts E-mail out of the picture altogether by just sending transaction records to a Web portal accessible by consumers. At the POS, consumers will get a text message confirming the sale, Lay said. "One of the things we were able to identify with consumers is they are a little worried about giving out their E-mail address for fear of retailers selling it," Lay said. "We also looked at what happens if a product breaks down. From a consumer perspective, we thought that going into an E-mail inbox and sifting through to find that receipt could take some time and is the same as finding a paper receipt in a shoebox." Some retailers considering adopting allElectronic's system apparently share our trepidation. They've suggested the company initially provide both paper and online receipts until its reliability is proven, Lay said.