The development of the Internet and email has brought about many changes in how people do business and communicate. It’s also made it easier for criminals to scam people.

The latest reminder of this came earlier this month with news of a cybersecurity lapse at Epsilon, an online marketing firm, resulting in the theft of millions of email addresses.

The marketing firm had email addresses of customers of Target, Walgreens, Citibank, JPMorganChase, L.L. Bean, Walt Disney, Barlcays Bank and others. And, since the discovery of the security breach, there have been warnings that email users could be subject to many more targeted scam attempts.

With the recently stolen information, emails could appear legitimate, because they will be sent to people with known relationships to legitimate businesses. The bogus emails could also contain authentic-looking graphics of corporate logos, adding to their appearance of authenticity. This makes millions of Americans more vulnerble to cyber criminals asking for Social Security numbers and bank account or credit card numbers.

Now, more than ever, people should be suspicious of any email asking for such confidential information.

News reports say that only email addresses were stolen. Thieves did not extract passwords, account numbers or other confidential information. Even if those reports are true, the cyber-thieves did steal enough information for them to pose a threat to millions of unsuspecting people.

Internet criminals often send out mass emails, trawling for trusting, unsuspicious people willing to part with personal information that can allow the scammers to empty bank accounts or process bogus charges to a credit card — or even to cause someone to write a check or send a money order to help a friend or stranger in need.

These mass emailing scams have been called “phishing,” as they try to extract information after casting a wide net. With the millions of stolen email accounts, experts are warning of “spear phishing,” which apparently means more-targeted scams. Epsilon reportedly sends out 40 billion — billion — legitimate emails on behalf of its clients.

Many of the potential scam emails will suggest that the point of the email is to “update your account information.” But people should view this phrase as a red flag, and insist on some method of communication to verify the authenticity of the email sender. Legitimate businesses will not ask for this information through email.

The best advice is for people to be, as always, very suspicious about emails requesting financial or personal information.

Beyond advising people to be cautious and suspicious, there is something the federal government could do to help reduce this sort of crime — apply some sort of fee for mass emailings.

When junk mail arrives in our mailboxes, the businesses sending the fliers or catalogs or envelopes had to pay to have the material printed and mailed or delivered in another way. With emails, there is no cost. Millions, even billions, of scamming emails can be sent for nothing. It’s no wonder criminal elements send billions of bogus emails — it costs nothing, and nets a few unsuspecting victims.

So, to reduce scamming mass emails, a small fee on sending emails could be applied. The revenue could fund electronic infrastructure or regulation of electronic communications. If an active email user sends 100 — or even 500 — emails a month, then a fee of a fraction of a cent for emails over, say, a 200-a-month threshold for free emails would have little or no cost. But such a small fee might inhibit those sending many millions of email messages that are junk, a scam or otherwise bogus.