Alexander: How spam e-mailers hide their identities

Q: Lately I've been receiving spam (unwanted junk) e-mails that come from invalid e-mail addresses. As a result, my security software won't let me add the addresses to its spam list for future blocking. What are the spammers trying to pull now, and what can I do about it?

Gene Borscheid, St. Louis Park

A: Unfortunately, there's not much you can do about it. You've encountered an old hacking trick called "spoofing," which means faking the originating address in an e-mail. Spam senders use spoofing either to hide their real e-mail addresses (so you can't add them to a spam-blocking list), or to fool you into clicking on an e-mail link because it appears to have been sent by a friend or a company that you trust. Spoofing is widespread because it's easy; there are even online tutorials explaining how to do it (see tinyurl.com/mqvalx8.)

The only real defense against spoofing is the screening done by e-mail providers before they send mail to your inbox, but that detection is hit or miss. For example, an e-mail service provider can identify a spoofed e-mail that originated within its own service. But, due to a lack widely accepted e-mail security standards, it's harder to identify spoofed e-mail from an outside source.

Readers who use such e-mail providers as Gmail, Outlook.com, AOL or Yahoo can try a technical trick that may temporarily block spam. By reading the e-mail's accompanying "source code" (see tinyurl.com/9melpmw) they can learn the "IP (Internet Protocol) address" of the spam sender's computer. All online computers have this identifying number, and most security programs can be set to block a specific IP address. But after enough blocked e-mails bounce back, the spam sender will just use another PC with a different IP address.

Although you can't stop spoofed e-mail, you can avoid it. If an e-mail address has misspellings or is quite long and contains blank spaces, it's probably spam. If a sender appears to be someone you know, ask yourself if that sender would e-mail you a message with links to click on.

Q: During a trip to Europe, we plan to use a smartphone as our GPS (Global Positioning System) unit. What kind of a portable changing device can we use when we don't have access to an electrical outlet? Is it better to have a charger or a second phone battery?

A: Your choice will depend on how often you need to recharge the phone while away from electrical outlets. Smartphone replacement batteries that you can swap out yourself cost $10 to $20 online (see tinyurl.com/onzm89e.) Replacement iPhone batteries are also available, but they aren't easy to change.

Alternatively, you can buy a portable charging device that will cost from $15 to $60 (see tinyurl.com/qbannrz). These devices are typically compatible with different phone brands and models. In addition, they can recharge your phone more than once before running out of power.