The Linux operating system is seldom targeted, but it can happen, and whether to play it safe by using anti-virus and anti-malware software is a judgment call, Patrick Marshall writes. He also answers questions about emails that fail to arrive and Windows 10 installation.

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Q: A while back, my local computer store installed Linux and Mozilla Firefox on my computer. We have AOL for email, etc. It has worked great since then with no apparent problems.

They said that it would not be necessary to have anti-virus and anti-malware because the “bad guys” don’t bother with Linux because it is not used by enough people. I actually cannot find any mention of anti-virus or anti-malware for Linux online. Everything is geared to Microsoft or Apple.

I would appreciate knowing your thoughts. Previously, we had AVG for anti-virus and Malwarebytes for anti-malware. Right now, per their advice, we actually do not have anything but also don’t seem to have any of the problems I read about.

Should we have them? And if so, which ones?

— Norman Marten, Bainbridge Island

A: There are some folks who say you don’t need protection against viruses and other malware on Linux. It’s true that malware is rarely found that targets Linux systems, but it does exist.

Fortunately, there are anti-virus programs and anti-malware programs available for Linux. Simply search the internet for Linux antivirus and you’ll find a number of offerings.

I can’t recommend any specific products, however, without running comparative tests. You can find one such recent comparison of 16 Linux anti-virus products at

The question is: How safe is safe enough for you? Even installing an anti-malware program doesn’t guarantee against getting infected by a virus or other malware, but it does make it less likely.

Q: Beginning July 1, every email I have sent to my sister-in-law comes back with the response that there was a “permanent error.” Also, when I send an email to Grandma’s email at, it comes back with the same rejection.

Somehow this problem is unique to my laptop because my wife has sent an email from her work laptop and her home laptop, which uses the same internet connection as my laptop, and both emails have been received.

Can you offer a solution?

— Robert Wainger, Redmond

A: You or your sister-in-law would need to contact her email provider to find out what’s going on. The details in the attachment you sent indicate that her email provider is detecting your message as spam.

That could conceivably be because someone may have been using your email address to send spam. Or it may be that the domain your email resides in has been blacklisted by her email provider.

Either way, I’d contact her email provider about the problem.

Q: I’ve made my switch to Windows 10, more or less successfully. However, my wife’s PC is more problematic.

While it’s new enough to switch over OK, she hasn’t let it upgrade. If I created a DVD for installing Windows 10 before the July 29 deadline but try to install it after the deadline, will I be stuck with paying for it? And will the same DVD work to install Windows 10 on more than one computer?

— Dave Mitchell, Renton

A: Yes, you can install on multiple computers using the same DVD. But each computer will need to have its own license. During installation, the installation program detects whether the computer is eligible for upgrade. If it is not, you need to buy a license.

During installation, Microsoft records a hardware “fingerprint” of your computer, which is recorded on Microsoft’s servers. As a result, you would be able to reinstall Windows 10 at no charge if you had installed it before July 29 and had for some reason uninstalled it.

There’s one caveat, however. Even after you successfully install Windows 10 if you change certain hardware in the computer, the operating system may detect the change in your computer’s hardware fingerprint and report that the Windows you’re running is not licensed. In that case, you may need to contact Microsoft technical support to get a new license code.

Unfortunately for those first trying to install Windows 10 after the July 29 deadline, if your computer’s hardware fingerprint hasn’t been recorded, Microsoft says it will require payment for the upgrade.