How can I test an email address to see if it is valid

How can I test an email address to see if it is valid? For example, Facebook allows you to create an account with an incorrect email address after verifying with a phone number. Is it possible to check for a valid email address and if so how?

Bishnu Bhattarai

Posted 2013-09-18T05:32:32.857

Reputation: 175

Those are all technically valid e-mail addresses. See: https://tools.ietf.org/html/rfc3696. Facebook will send you a confirmation e-mail though, so if you enter a non-existing address you cannot use its services: https://www.facebook.com/help/376335499080938 – questions about web applications are off topic though.

– slhck – 2013-09-18T05:48:00.690

Precisely define what you mean by "valid" and then see if the email address meets that definition. – David Schwartz – 2013-09-18T06:45:59.093

Answers

If the operating System is Windows you can verify by doing the following

To do it Follow these steps

1.Open Command Prompt

2.Find the exchanger of the domain By nslookup

   nslookup – q=mx gmail.com

3.Connect to mail Server using telnet

   telnet gmail.com 25

4.once you get the response

type some message hi ,hello

   mail from: <youremail@gmail.com>
   rcpt to: <test12345666@gmail.com>

5.If you get response code 550 then the recipient address is invalid

6.If email is vaild the mail server would respond back with code 250

Alternatively you could test using some online email checking tools like mailtester .

BlueBerry - Vignesh4303

Posted 2013-09-18T05:32:32.857

Reputation: 7 221

There are 3 ways that I have seen sites validate email addresses.

test for valid email address syntax of the form username@domain.com
test for 1 and if it passes then test that the domain is valid by doing a whois lookup of the domain. #whois domain.com;
test for both of the above and if the address passes, then send a unique link to the email address that has to be visited by the user or send a unique code that has to be entered into a web form.

Michael Yasumoto

Posted 2013-09-18T05:32:32.857

Reputation: 583

If you read the RFC http://tools.ietf.org/html/rfc3696 you can end up wtih regular expressions like this ones http://www.regular-expressions.info/email.html

finally test your regexp at: www.regexpal.com

Zesar

Posted 2013-09-18T05:32:32.857

Reputation: 359

Easy way I found is online email validity checking tools like vefify email and email checker

Renju Chandran chingath

Posted 2013-09-18T05:32:32.857

Reputation: 1 461

I'm inclined to like the first tool, but I tried an email address on my domain that I know exists and another one that I know doesn't, and they both say "UNKNOWN". So it looks like it doesn't work. – InterLinked – 2018-07-10T21:08:55.087