A few years ago, a reader asked me a question I couldn't immediately answer. "I know that, when you toss an old computer, you're supposed to make the personal information that resides on the hard drive inaccessible to the outside world," he said. "I was wondering if this same issue arises when you toss an old printer?"

It’s a good question. Certainly, you need to thoroughly sanitize any computer you plan to give away or recycle, ensuring none of your personal information remains. The same is true when you trade in or sell a smartphone. Could these concerns exist for printers, too? To get a handle on this question, I turned to M. David Stone, PCMag's longtime contributing editor for printers and scanners.

What Kind of Data Do Printers Hold?

"First, you need to make a distinction between types of data," said Stone. "The important stuff for most people would be what you print, fax, or copy. Call that real data. The less important info would be stored email addresses and fax numbers. Call that contact information."

Stop and think for a moment about the most sensitive data you print, fax, or copy. Tax returns? Legal documents? Medical records? Some medical practices prefer communication by fax machine, on the basis that it’s more secure than email. But if the sensitive information sits in the all-in-one device’s memory, that’s far from secure.

"The only time any information stored on the printer can be an issue is if the printer has either an internal disk or non-volatile memory," he continued. "I also doubt there are any with non-volatile memory for real data, but I can't swear to it. There are some that can hold contact info in non-volatile memory."

How to Tell if Your Printer Stores Data

Stone pointed out that the presence of certain features might indicate the presence of onboard storage in an old printer. Private printing, where the printer holds your document until indicate that you're physically present to receive the printout, would seem to require local storage, as would the ability to reprint a file that you printed earlier. The ability to manage and reorder the print queue via the printer's embedded web page is another sign, as is an option to hold or forward incoming faxes.

If you really want to check for stored sensitive data, Stone suggests you unplug your old printer, let it sit for a while, and plug it back in again. No local storage? Then the data will likely be gone. "Note that in some cases the printer may be using volatile memory with a battery backup," added Stone. "If it is, this should be mentioned in the user guide." In that case, he suggests leaving it unplugged for however long the user guide says is too long.

Does Your Printer Store Your Email?

Stone warns about an electronic recycling danger I hadn't considered. "Multi-function printers that include a direct email function (as opposed to the ones that call up a client on your PC), typically have you set up SMTP info, including your password, so you can send email from the printer's front panel," he warned. "If you've set that up, make sure you delete the email and password before you hand the printer to someone else."

He also pointed out that these days most of the expensive printer models that do include a disk drive take privacy into account. "Almost all new models include a wipe disk function for decommissioning the printer, and most include disk encryption, so if you take the disk out of the printer you won't be able to read the information stored on it," he explained.

Should You Physically Destroy an Old Printer?

If you're getting rid of an old printer, it's probably because the printer is either broken or too outmoded. It's unlikely that there's a hard drive inside, but if you're truly junking the device, you can take some physical precautions. Open it up, poke around, look for anything remotely resembling a hard drive. If you find one, extract it from the printer, take it out to the street, and bang on it with a hammer until the insides rattle nicely. (This is very satisfying!). Now you can send the printer off for electronic recycling without any privacy worries.

So Is It Safe to Throw Out Your Old Printer?

Stone points out that modern printers may have additional connections to your other apps, more than just stored email credentials. For example, they may scan to or print from cloud storage services such as Google Drive or DropBox. Before disposing of such a printer, you should break those connections. Doing so may involve clearing a stored username and password from the printer, or it may be a matter of logging into the service and cutting the connection from that end.

Stone also notes that many major printer brands let you associate your printer with a company account online. “For example,” he said, “I can set up an Epson account that will let me print from anywhere in the world.” He noted that you don’t have to cancel the account, just dissociate it from the departing printer. After all, you might get a new printer from the same company.

As for pulling the hard drive out of a printer and using it as a hockey puck, that’s still a valid hardware-based solution. “We might someday see a printer with an SSD for storage rather than a hard drive,” he said, “but it hasn’t happened yet.”

It's Surprisingly Easy to Be More Secure Online