(CBS) — Most of us open dozens of emails every day, but did you know some of them are likely being tracked?

CBS 2’s Mai Martinez takes a look at who could be tracking you and what they’re doing with the information they get.

Open any email and you could be giving away information without even realizing it thanks to email tracking software.

How does it work? A tiny image linked to a code is embedded in the email. Once the email’s open, the sender knows when, where, how, and even more.

“When you read the email, how long you were reading it, where you were geo located, what kind of computer you’re using, what kind of web browser or email client and if you clicked any hyperlinks downloaded any attachment or even sent that email onto others,” said cyber security expert Gary Miliefsky.

DePaul University computer science professor Jacob Furst says companies have tracked emails for years, and now it’s going mainstream via options like Bananatag, Streak, and Mail Chimp.

“It’s a broad spectrum of people who might want to track emails for a lot of different reasons,” said Dr. Furst.

Businesses use tracking to see if their emails are getting attention, and now people are doing the same.

Photographer Bob Johnson, who’s looking for a job, is one of them.

“I know that my resume has gone where I sent it,” Johnson said. “I know how many times it’s been opened, if an email has been opened six times, I know there may be some interest and maybe I’ll get a call.”

“There’s no content being recorded, it’s just information about this exchange and that’s perfectly legal,” said Dr. Furst.

It can also be quite profitable, just ask Review Trackers CEO Chris Campbell. More than 10,000 businesses pay his company for monitoring.

“We’re helping businesses better understand who’s opening their emails, maybe who’s clicking on the links inside the emails,” Campbell said.

Campbell said the tracking information is, “basically a log of all the activity they take, any interactions they have with the email.”

While the information being tracked may seem harmless, experts say people still need to know it’s being gathered.

Dr. Furst says, “Be diligent. Be vigilant. Make sure you at least know what’s going on.”

Want to avoid having your email tracked? Experts say just read your email in “text only” mode, so tracker images and attachments won’t be downloaded.