Google ignores the periods in your email address.

That means johnsmith@gmail.com and john.smith@gmail.com are the same email address.

You can use this trick to filter out spammers and companies that sell your email address.

My personal email address is my name at gmail.com. Most of the time, it looks like this: kif.leswing@gmail.com.

But if I end up giving you kifleswing@gmail.com, don't worry. I'll still get the email.

In fact, if you're a Gmail user, the periods in your email address don't matter at all. Gmail completely ignores them. You can add or remove as many periods as you'd like.

Here's how Google explains it on a help page:

If someone accidentally adds dots to your address when emailing you, you'll still get that email. For example, if your email is johnsmith@gmail.com, you own all dotted versions of your address:

john.smith@gmail.com

jo.hn.sm.ith@gmail.com

j.o.h.n.s.m.i.t.h@gmail.com

Gmail is one of the few services in which the dot doesn't make any difference in your username. Slate writer Will Oremus previously found that Facebook doesn't care about username dots, either, but nearly every other online services does.

Also, if your workplace uses Gmail, that doesn't mean you can stick periods in your work email — it only applies to @gmail.com addresses.

A secret spam address

While periods in Gmail usernames can be a fun quirk, they can also be a useful way to sort your inbox and filter what lands there.

Because the dots effectively give you scores of alternate email addresses, you can pick one and make it a defacto spam folder.

For example, if everyone emails me at john.smith@gmail.com, that should remain my main email address. But every time I'm giving my address to someone who might spam me, I give them john.smit.h@gmail.com.

Then, in my gmail, I can create a folder for all mail sent to john.smit.h@gmail.com, and automatically star, or archive, or delete those notes. You can also use extra periods to sign up for a second account on a website without creating or using a new email address.

This trick also works with the + symbol, which can be used in any email address to create even more alternative addresses. "For example, if your name was hikingfan@gmail.com, you could send mail to hikingfan+friends@gmail.com or hikingfan+mailinglists@gmail.com," Google explains on a help page.

"You can also use this when you register for a service and think they might share your information. For example, I added "+donation" when I gave money to a political organization once, and now when I see emails from other groups to that address, I know how they got it. Solution: filtered to auto-delete," Google continued.

So while you don't have to stop telling people about the period in your email address, you should be aware of the superpowers it gives your Gmail account.