How can you test that an email is real?

[conjurer]

I know how to write some scripts to verify the formatting of an email address entered in a form to ensure it is [e-mail]

But that doesn't check it to see if it is a live email address that will actually work. For instance I could type [e-mail] and most validation script will accept it as a possible email.

What I am wondering about is if there is a way with PHP to actually go out on the web and test the entry so that you can determine that it is a real working email site. Does anyone know if this is possible, and if so, how would you do it?

[Pig]

There is no way to validate it absolutely, other than making the user respond. That is why many sites have you receive an email with an activation code before finalizing a new account.

[The_Chancer]

Another possible option is to get the mail to trigger a dynamic image, that will capture the email address. This'll only work though with the mail clients that support this.....

[conjurer]

I thought that might be the case. I am planning to use an activation code, but was concerned about the couple knuckleheads that don't check there email closely enough and enter one that doesn't work.

At least we will know that they haven't activated their account.
Thanks

[dalecosp]

Originally posted by conjurer
I thought that might be the case. I am planning to use an activation code, but was concerned about the couple knuckleheads that don't check there email closely enough and enter one that doesn't work.

At least we will know that they haven't activated their account.
Thanks

This is why most such "activation emails" include a clickable link with the auth code embedded in it. Not 'fool-proof', but more 'fool-hardy' than what you seem to have in mind.

🆒

[ajdegans]

Might want to use this? 😛

//messages
$error_1="<center>All fields must be filled in!</center>";
$error_2="<center>Given email nog valid!</center>";
$error_3="<center>Email error, Check config!</center>";
$success_1="<center>Message send!</center>";

//Emailhost (comment this line if not needed !!!!!)
ini_set('SMTP', $emailhost );

//Emailform
echo "<center><div class='contactform'>";
echo "<form action='' method='post'>";
echo "  Naam: <br><input type='text' name='name' size='30'><br>";
echo "  Email adres: <br><input type='text' name='email' size='30'><br>";
echo "  Onderwerp: <br><input type='text' name='subject' size='30'><br>";
echo "  Bericht: <br><textarea name='message' cols='40' rows='5'></textarea><br><br>";
echo "  <input type='submit' name='submit' value='---- Email Sturen ----'>";
echo "</form>";
echo "</div></center>";

if ($submit) 
  {
  if($name && $subject && $email && $message ) 
  { 
    if(!eregi("^[_a-z0-9-]+(\.[_a-z0-9-]+)*@[a-z0-9-]+(\.[a-z0-9-]+)*(\.[a-z]{2,3})$", $email) )
	  { echo "$error_2"; }
	else { mail("$emailadres", "$subject", "$message", "From: $name <$email>") or die("$error_3"); 
	echo $success_1; }
  }
	else { echo "$error_1<BR>"; }
} 
?>

it uses an field check to see if all fields are filled in, if not it shows an error.

it uses simple email validation... if no @ init its declined

g/l😃

[drew010]

it is possible to check if an email address exists. what you do is simply connect to the remote smtp server for their address and if the server supports it use VRFY and the server will tell you if the username is valid as a mailbox or not, if vrfy is not supported you can try RCPT TO email address and it will give mailbox unavailable if the user doesnt exist. just as a warning some large sites, will say 200 ok for any email address, but a majority of mail servers will tell you if the box is unavailable.
a sample session may be
connect mailserver port 25
helo yourserver
mail from: [e-mail]
help
if vrfy is contained in return string
then it supports the vrfy command
vrfy user
if 200, box exists
exit
else
no vrfy, use rcpt to:

rcpt to: [e-mail]

if return status is 200
mailbox exists, email accepted
else
bad status, box unavailable
quit

additional note, if a box doesnt exist but the mail server says so, it may mean there is a default catchall for the domain, otherwise if a message is sent, it will just return the message.

if you need more info on the mail server stuff or help w/ this program. contact me thru email (drew [at] drew-phillips (dot) com.
or chat line
look in my profile for details
i made something like this a while back for a person, dont hve the code anymore but could certainly help you write a php block for it.

[dalecosp]

I wouldn't give that strategy a really "reliable" rating, but it is a possibility. I'm doubting the "most servers" statement....

My own research shows that most servers for big networks support VRFY, although many of them will give a 5xx code if the user is non extant. AOL returns a 550 is RCPT TO: is given to a non extant user; so does Earthlink. Yahoo! returns 554 after the DATA is sent... Many servers, however, don't even care... and I've found some that claim to VRFY and then state "Cannot VRFY user, but will take message for <[e-mail]>

As the spam problem on the Net shows, we really need some genius to rethink MTP ....

[edit]that should read "big networks DON'T support VRFY"[/edit]