Last April, two mild-mannered Phoenix lawyers posted an advertisement for their immigration law practice on the Internet -- and instantly became the country's most vilified husband-and-wife duo since the Rosenbergs, or at least Tom and Roseanne.
   For the transgression of sending what amounted to unsolicited electronic junk mail over the publicly owned Internet, Laurence Canter and Martha Siegel became the targets of a tar-and-feathering in cyberspace.
   The hate mail, electronic "flame mail" and threats poured in by the tens of thousands, from outraged Interneters who considered the blatant commercial pitch a violation of network ethics.
   Their home address was published, and people were urged to burn down their house.  Hundreds of unwanted magazines and mail-order products were ordered in their names.  Information "bombs" clogged their electronic mail box.
   It may have been the best thing that ever happened to them, opening the path to a marketing company, Cybersell, and a new book "How To Make a Fortune On the Information Superhighway (Harper-Reference, $20).
   "We're not martyrs," Siegel said during a visit to promote the book.  "We're marketers."
   Canter and Siegel said they didn't exactly set out to make advertising history when they developed a technique for automatically broadcasting commercial messages on the Internet, a practice that has since been dubbed "spamming."
   They were just looking for a lo-cost way of reaching an audience, and the Internet's estimated 30 million (give or take 10 or 20 million) participants looked like a perfect untapped opportunity.
   "We didn't feel it was intrusive," Siegel said.  "We advertised on public bulletin boards, which people look at their leisure."  Rather than junk mail or telephone solicitation, she said the practice was more closely analogous to TV advertising.  If you don't like it, you can always change the channel.
   Canter and Siegel, who said they got hundreds of responses and $100,000 worth of business from their Internet postings have set up company offering services on information superhighway marketing techniques.  They've also set up an entertainment division.