How do you know if an email address exists or not? The easy option would be that you send a dummy mail to that email address, wait for an hour or so and if your message bounces, it is very likely that the particular email address does not exist. The approach works but wouldn’t it be nice if you could check any email address instantly without even sending that test message?

The other slightly technical option to verify an email address is by querying the mail server. You connect to the mail server through telnet (see video), enter your email address and the other email address that you are trying to verify. If the server response is an error code, the email address is probably not valid.

How to Check Email Addresses Instantly

Let me share an extremely simple method for checking if an email address is valid and exists or not.

Go to the login page of the email service and pretend that you no longer remember the password of your email account. The service will ask for your email address where they can send the password recovery instructions. Here if you enter an email address that does exist, the service is mostly likely to tell you that the particular user name does not exist. I have tested this with Google Apps, Yahoo Mail and Outlook (Hotmail) and the method works with them all.

For Gmail and Google Apps Accounts

Go to Google’s password assistance page at google.com/accounts/recovery and choose the I don’t know my password option. Enter the email address that you are trying to verify - it could be an @gmail address or a Google Apps address - and choose Continue. If that address is not valid, Google will throw an error saying No account found with that email address.

Alternatively, you can go to the Gmail Sign-up page at accounts.google.com/SignUp and try creating a new Gmail account with the address that you are trying to verify. For valid email address, the error would say Someone already has that username.

For Outlook, Hotmail and Live.com Addresses

Go to account.live.com/ResetPassword, choose the I forgot my password option and enter the Outlook email address. You will get an error saying The Microsoft account is incorrect. for addresses that do not exist.

For Verifying Yahoo Email Addresses

Go to Yahoo’s account recovery page at edit.yahoo.com/forgot, enter the @yahoo.com email address that you are checking for validity and click the Next button. Yahoo will say We couldn’t match the Yahoo ID you entered with information in our database if the email address does not exist.

Related tutorial: How to Guess Someone’s Email Address