Lorrie Cranor never sends electronic cards, and she rarely opens the ones sent to her. For the Carnegie Mellon University associate professor of computer science and engineering to feel confident that those little greetings aren't bad news, she needs checks and double-checks.

She admits she's probably deleted legitimate e-cards from friends. Oh, well. "It's my job to be paranoid about these things," she said.

A nation of lovers, or at least many friendly people, is coming up fast on the biggest e-card sending occasion of the year, as rated by the Greeting Card Association, in Washington, D.C. The industry estimates 15 million e-Valentines will be sent over this year's holiday.

And while old-fashioned cards made of paper still far outnumber the digital ones -- the card association estimates 190 million Valentine cards are exchanged every year, not counting the type school kids hand out -- card companies that sell both have settled into a sort of ongoing vigilance against cyber sneaks.

"We work really hard to educate people on what a real e-card looks like," said Sarah Kolell, a spokeswoman for Hallmark Cards Inc., based in Kansas City, Mo.

The private company doesn't divulge a lot of financial information, but there's money in the e-card business. In June, Hallmark changed from a policy of offering a lot of free e-cards and then some special ones for $1.49 each to a system of charging 99 cents each for most e-cards. Or users can buy a $10 annual subscription and send all they want.

Ms. Kolell said the fee change was done, in part, because the most popular e-cards tend to be those that include licensed characters, such as characters from TV shows. Both Hallmark and Cleveland-based American Greetings also have staffs to develop music and new designs for their e-cards.

It's a little different for the greeting card industry to fight spam than, say, banks, which regularly put out statements urging customers to ignore Internet inquiries asking for account details. The financial institutions can usually just advise people to ignore those e-mails because that's not how they contact customers.

But electronic greetings do use the world's e-mail delivery system to reach their recipients with dancing sock puppets or goofy love songs.

Generally, the companies said people don't use e-cards as the main Valentine's message to their significant other. Rather they might send them to friends or distant family. Then again, in a week when much of the East Coast and parts of the Midwest are buried under snow drifts, an e-card may be an alternative to going to the store to buy a card.

Although there hasn't been a big increase of late in the percentage of viruses and threats using e-mail, including e-cards, to spread, there's plenty of that sort of thing going on, said Grace Paik Kim, a public relations manager with Symantec Corp., a computer security company. In 2008, 31 percent of "malicious code samples" that spread virally had the ability to do so through e-mail attachments, according to the company, based in Mountain View, Calif.

Companies such as Hallmark and American Greetings and even the card association put e-card safety tips on their websites, including advice not to click on links or download things. "In order to see an e-card, you never have to click on anything," said Ms. Kolell, at Hallmark.

An American Greetings spokeswoman agreed, saying most reputable sites suggest recipients go to the company's main page by typing -- not copying and pasting -- in the site address. Then consumers can enter the code found in the original e-mail to retrieve the greeting.

Red flags to watch for in e-cards include terms such as "secret admirer," "special friend" and "it's you."

Ms. Cranor said people are more easily fooled than they might think, especially around major holidays. A birthday e-card might be harder to get people to open since that would mean knowing their birth dates; but Valentine's Day is the same for everyone.

She was involved in research not long ago in which her group sent fake scam messages to addresses of Carnegie Mellon students and staff. Even at CMU, known for having tech-savvy types around, people fell for such things as offers for a $100 meal card and an e-mail impersonating a CMU office that requested a password. The only one that no one fell for was one about community service.

If people did click on the link that might typically introduce something bad to their computer, the research group's program took them to a website with training on how to spot spam. Ms. Cranor was part of a group that then launched a company called Wombat Security Technologies to sell training games.

At the moment, the company's products don't focus on e-cards, but Ms. Cranor said it's been discussed. "It's on the list to add to our training." Meanwhile, she'll stay on her guard.

The card companies are developing other uses for the latest technologies. Those include mobile e-cards sent between cell phones and printed cards that show off 3D images when held in front of a webcam.

In addition, Hallmark's Ms. Kolell pointed out, there's the service in which online customers can select a paper card, put a message on it, address it and stamp it. There won't be any dancing hamsters, but the card company does take care of getting it in the mail.

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