Q: In December I switched to a Samsung Galaxy 4 smartphone from a BlackBerry. While I can receive e-mail on the phone from my two Comcast e-mail accounts, the e-mails I send from the phone through the Comcast e-mail system aren't being delivered. I haven't been able to get a solution from T-Mobile or Comcast. What can I do?

Kathy Vegoe, ST. Paul

A: There have been many online complaints about the difficulty of using Comcast e-mail on Android (and occasionally Apple) smartphones. For a sample of complaints from July through December of last year, see tinyurl.com/l8ot9rm. The most reliable fix appears to be using the Xfinity Connect App rather than your phone's own mail app. Download instructions can be found at tinyurl.com/4ys9d3d (for Android phones and tablets) and tinyurl.com/kqt9yvo (for the iPhone, iPad and iPod Touch).

The alternative is to switch to a less troublesome Web e-mail, such as the free Google Gmail (tinyurl.com/kot wuys) or Yahoo Mail (tinyurl.com/mhxy8vt) services.

Several readers questioned my advice that international travelers protect their electronic gadgets by using both electrical adapters (for wall outlet compatibility) and an electrical converter or transformer (to adjust the local voltage to the device's level.) They noted that many devices can handle different voltages, and thus don't need a converter or a transformer.

It's true that many of today's gadgets are dual-voltage or multi-voltage and thus don't need voltage protection, but not all devices have these safeguards. For details on how to identify which gadgets need protection, and which don't, see tinyurl.com/n4kpcpv and tinyurl.com/l7s48ua.

Q: When I turn on my 2004 Windows XP computer, it warns me that the firewall is not turned on. But, for reasons that aren't clear, I haven't been able to activate the firewall. Meanwhile, my security software is detecting a lot of viruses on my PC. What can I do?

James R. Smith, New Brighton

A: There are three answers.

One: You can turn on your Windows XP firewall by going to Control Panel and double-clicking Network and Internet Connections, then clicking "Set up or change your home or small office network." Follow the steps outlined by Microsoft's "Network Setup Wizard."

Two: If that doesn't work, you can download a free firewall for Windows XP at tinyurl.com/mcodzvk (Comodo Firewall) or tinyurl.com/msvxe3a (Ashampoo FireWall Free).

Three: Buy a new Windows 7 computer (still made by HP, Asus, Dell and others). Avoid the confusing Windows 8. Microsoft is discontinuing security updates for Windows XP in April.

E-mail tech questions to steve.j.alexander@

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