In-person job interviews typically last between 45 and 90 minutes, according to job search site Indeed. In that time, you'll probably be asked about your work history and be told about the role you're interviewing for.

When the interview's over, It's customary to send a thank you email to everyone who interviewed you within 24 to 48 hours — but if you want to go that extra mile, send a physical thank you note as well.

"Hardly anyone does that ever," says Vicki Salemi, career expert at Monster. But it can pay off — here's why.

It shows you 'really put in the effort'

Interviewers likely speak with many candidates, many of whom will remember to sent over a thank you email after they meet. But most probably won't send anything by snail mail.

"A handwritten thank you note can help you stand out in the job interview process," says Angelina Darrisaw, a former manager at Viacom and CEO of C-Suite Coach. "It can signal that you are willing to go the extra mile, which can be very attractive to potential employers."

When you see someone's handwriting, it feels like you "really put in the effort," says Salemi.

Not only will they remember that you were willing to go a little further to show your gratitude about the interview and excitement about the role, but they'll have a physical reminder of it sitting right in front of them.

Salemi remembers the effect these notes had when she was a recruiter herself. "As we were determining who was going to get the job offer, I had that thank you note on my desk for at least a week," she says. "And I always thought of that person."

'It's a nice touch'

Your thank you note does not need to have any particular flair. "You can get boxes of note cards that just say 'thank you,'" says Salemi.

To get a physical mailing address, ask for a business card or see if there's an address in the interviewer's email signature. There might be an address on the company website as well, but be sure to include the name of their department on the envelope.

When it comes to what to write, keep it simple and include variations of the following:

• "Thank you for the opportunity to meet you"
• "I'm excited about this role"
• Something specific you talked about in the interview

Always double check your writing before you put it in an envelope to make sure there aren't grammatical or spelling errors.

Salemi recommends writing the note directly after the interview, once you've left the building — maybe in a nearby coffee shop — then dropping it off in the mail as soon as you're done.

"It's a nice touch because then a few days later, the interviewers are busy with their normal work lives and they get this on their desk," says Salemi. When it comes time to decide who's right for the role, you will be top of mind.

CNBC