TULSA, Oklahoma - Despite all we can do online these days, you sometimes still need to write a check to pay a bill by mail.

It's so convenient to put that bill in your mailbox so the letter carrier can pick it up, but doing that is just asking for trouble.

I know I've told people this before, but it bears repeating: if you are sending a check or some type of money through the mail, you have to take it to a blue mail box or drop it off at the post office. It may seem like a hassle, but it's much better than the hassle you'll face if a thief gets to your mail before the mailman does.

Despite all the warnings, it's easy to find mail sticking out of mailboxes. People put it there, knowing the letter carrier will take it in for them, but that mail is very enticing to thieves. Just ask Brian Sheehan.

"Stupidly, I left them sticking out the top, just like that, with the majority of it showing, the stamps out there. They were kinda obvious," Sheehan said.

They were obvious enough for a woman driving by to see them and come help herself. Sheehan's motion-activated security camera caught a short video of her walking back to her car afterward.

Every time the camera is activated, Sheehan gets an email.

"The worst thing about it was knowing someone was brave enough and bold enough to come up to my house in the middle of the day time and steal my mail," he said.

Thanks to the early warning, Sheehan got his checking account shut down before the thief could start shopping.

Thieves do it by washing your check with a solution to remove the name and amount you wrote, then they write in a new business name and amount, or they simply print new checks from yours and off they go, spending your money.

I talked to a postal inspector, who said you might as well just tear off the little red flag on your mailbox, because when you put it up, all it says is, "Come steal me."

Sheehan installed his little camera just to see what happens on his front porch while he's away. He sees the mailman approach every day, he saw me walk up to the door for our interview, and he even had short videos of us on the front porch during the interview.

In this case, he only got the woman walking away, so maybe she approached from the side, but he hopes she'll be identified and prosecuted.

"If it helps a couple of people from not getting their mail stolen, it'll be worth it," Sheehan said.

If you're receiving checks in the mail, get a locking mailbox or install a mail slot in your door or have them delivered somewhere else, like your workplace, where you can get your hands on them quickly, and they're not sitting in your box all day until you get home.

I've interviewed mail thieves in the past, who told me they opened hundreds of mailboxes a day, looking for things to steal.