E-mail Validation with PHP

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This tutorial will show you how to check to see if an E-mail address is valid.

By : David Duke

This tutorial has been graciously provided by spoono.com

When you register on at a website, the site normally checks if the e-mail address that you enter is in a valid format. This is done by using what called a Regular Expression. What we need to do is check if a string (eg $email) matches the regular expression:

<?php ereg("^[a-zA-Z0-9_]+@[a-zA-Z0-9\-]+\.[a-zA-Z0-9\-\.]+$]",      $email); ?>

At the moment that only checks the string ($email), but does not does not output anything.So next we need to write an IF statement that returns a boolean value, if the string does not match the regular expressions.

<?php if (eregi("^[a-zA-Z0-9_]+@[a-zA-Z0-9\-]+\.[a-zA-Z0-9\-\.]+$]", $email))  {    return FALSE; } ?>

That is the basic validation bit, but now we can do even more validation. What we will do next is check the domain name after the @ is a real domain name. (We do this by checking if an MX record exists for that domain name and then we check if port 25 is open for that domain name, which makes sure that the domain name is in use.)

<?php list($Username, $Domain) = split("@",$email); if(getmxrr($Domain, $MXHost))  {    return TRUE; } else  {    if(fsockopen($Domain, 25, $errno, $errstr, 30))     {       return TRUE;     }    else     {       return FALSE;     } } ?>

Next: Finishing it off >>
 

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