If it's spam, it's scam. "Unsolicited e-mail is always bad news," said Jim Lanford, editor of the Web site Internet ScamBusters. "Never respond to bulk e-mail." Other hard-won advice:
Plastic, not paper. Credit cards are the safest way to buy things online, because if you do get ripped off you can dispute the charge. And if your card number is stolen, you're liable for only the first $50, which banks will often pay anyway if you're a good customer.
Leave a paper trail. Use your printer. Hard copy makes better evidence.
Look before you leap. Sometimes what looks like a store is actually a front for extracting personal information. Don't think it's only money you're giving out; you're also giving out your details, which are often more valuable.
Use it so you don't lose it. Online auctions have developed some effective protection services. The trick is to use them. eBay has a helpful feature called the Verified eBay User program. To become verified, an eBay user submits detailed information, which is then reviewed by credit agency Equifax. Most major auction sites have partnered with a respectable escrow service, but watch out for lesser-known firms: Some reportedly keep your money as long as possible to collect interest.
Avoid the kindness of strangers. Whether you pick up investment advice from a chat room or an unsolicited e-mail, if the ultimate source is a complete stranger, keep looking.