We never knew we had so many globe-trotting friends. They've been checking in from London, Madrid, Edinburgh and other places we'd love to visit.

At least we thought so.

You see, our friends are having a run of rough luck.

Mugged. Their money and credit cards stolen. Passports, too. Greeted with indifference at the embassy, by the airlines and their hotels. How frustrating. How frightening. Yet somehow they have managed to send an email or instant message asking us for help.

What can we do? Shall we wire some cash? How about a credit card number?

What's that? You say your friends are in the same predicament?

OK, it didn't take long to realize that email accounts had been hacked and address books used to personalize appeals for cash. Of course, those confidential offers from deposed third-world potentates with oil wealth to share and the notices that we'd won the Irish sweepstakes — just pay a processing fee first — were pretty transparent, too.

Nevertheless, people respond, sending money, sometimes thousands of dollars, and even bank account numbers. Senior citizens are especially vulnerable to Internet, mail and telemarketing fraud, and that's a big reason why these contemptible schemes aren't just costly examples of caveat emptor.

The federal Internet Crime Complaint Center, a multi-agency effort to crack down on these scams, receives more than 25,000 reports each month, and annual losses from Internet-based fraud exceed $200 million.

Staff Writer Julie Johnson recently told the story of an 87-year-old Petaluma woman who, having received a call saying her grandson was in jail, sent $7,500 for bail. Soon she was receiving demands for more money, followed by death threats when she refused.

Listen to her rueful explanation and you might hear your own parent or grandparent speaking. "It's terrible what people do today," she said. "Everyone wants money. When I grew up, people were trusting and would help each other any way they could. I just don't know what to think."

Americans opened their hearts — and their wallets — after the Sept. 11 attacks and again after Hurricane Katrina devastated the Gulf Coast states in 2005. With the 10th anniversary of 9/11 approaching and Atlantic Coast states recovering from Hurricane Irene, authorities are warning people to look out for new scams — pleas for money to help survivors or for rebuilding efforts.

The Internet Crime Complaint Center, or IC3, offers tips for avoiding scams, such as not responding to unsolicited email or accessing charity websites through emailed links, donating only to organizations you're familiar with and donating directly rather than allowing others to do so on your behalf. Above all, don't provide birth dates and other personal information.

Otherwise, you're more likely to be a victim than any "friend" stuck in a London airport.