Verifying email addresses

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01/01/03 "Removing bogus email addresses"

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Dealing with bogus email addresses

Hopefully no big New Year's hangovers are abounding, right?! Today, I decided I wanted to wish folks on the php-scripts.com mailing list a happy new year and lo and behold I was seeing all kinds of bogus email addresses like a@a.com ... I started removing them manually and about a half-dozen emails into the process I said to myself: what am I doing? I should be using PHP for this! So I set about reviewing the php mailing list program I had created quite some time ago.

Creating your own mail list was originally discussed in these diary entries:

Sending email using PHP 010100.php3
Using loops in PHP to send mail to multiple recipients 010200.php3
Sending email using PHP 122899.php3
Building a mail list using php 122999.php3
Building an email list - unsubscribing from mail lists 123099.php3

By the way, that list came from search results from the php meta tag diary search that I show you how to build in the diary entry: 010600.php3 -- try adding that to your website, you'll find it very handy ;)

Alas, I had discovered that while I was checking the syntax of the email addresses entered, I wasn't checking the validity. It was time to take the following actions: 1) validate and remove bogus email addresses from the existing list and 2) update the existing subscribe script to validate email addresses at the time of subscription.

How to check the validity of email addresses: verification

Outside of sending a validation mail there isn't a 100% full proof method, but one could use a technique like logging into the mail server and sending a hello message and/or using a handy built-in php function called:

getmxrr - PHP Manual reference: http://www.php.net/manual/en/function.getmxrr.php

So let's take a couple of bogus email addresses from my list and see if it properly strips out these two bogus emails a@abc.com b@123.com

$addys = array('a@abc.com', 'b@123.com');
$sizeaddys = count($addy);
for($i=0; $i<$sizeaddys; $i++) {
$parts = explode("@", $addys[$i];
$host= $parts[1] .".";
     if (getmxrr( $host, $mxhosts ) == FALSE &&
        gethostbyname( $host ) == $host ) {
         // add to good array
         $success_email .= "$addys[$i]";
     } else {
         $failed_email .= "$addys[$i] ";
     }
}

print("<br>Failed: $failed_email<br>Success:$success_email");

Notes:
1) allow the above script some time to run as it checks out the bad addresses. I added some additional enhancements like flushing the output in the source.
2) comments in the PHP manual indicate that this technique doesn't work on Windows systems. I have only tested on *nix servers.

Freeware PHP Scripts worth checking out
Have some fun with 3D graphs: php3DLib - http://dev.e-taller.net/3dlib/

Happy coding to you!
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