email validation

[slimjim]

I have been reading this stuff all day long, and still lost.
How do validate a email address is in right format and also check if the domain is actually a domain and not bogus and at same time, update a database if valid and message if not ?

Anyone have some code to share on this issue. Driving me nuts.........................

[bretticus]

well, the email format isn't too hard with the right regular expression function:

if (eregi("^[a-z][a-z_0-9\.]+@[a-z_0-9\.]+\.[a-z]{2,3}$", $_POST['email'])) //email is in proper format...

//as for the domain check, you can use the following sockets code and parse the content it returns to determine a valid domain. 

$domain_to_check="somedomain.com";

$sock=fsockopen("whois.arin.net", 43, $errno, $errstr, 30);

		if(fputs ($sock, "$domain_to_check\r\n")) {
			while (!feof($sock)) {
				$out .= fgets ($sock, 2048);
			}
			fclose($sock);
		}

I heard a rumor about whois changes the other day (something like a whois query being a multilayered transaction) so the socket code may not work like it used to. Worth a try anyways.

P.S.

I suppose a more obvious approach might be to use gethostbyname()

I just mentioned the sockets method as

I don't remember how long it takes to timeout on a bougus domain with gethostbyname()

[slimjim]

How with that code, Would I get the domain name out of the email address ? I know it has to do with after the @, I will not know the domain name, so putting it in manually would be normal thing to do. I would think I would have to break it up or something.

And if it is a valid domain, at what point do I update a database ? ANd if it isnt, do something else.

[slimjim]

Here is all the further I got today, and still havnt figured out how to tell if it is a actually a good email address that exsist...

$email = $_POST['email'];
if(!eregi("^[a-z0-9]+([_\\.-][a-z0-9]+)*". "@([a-z0-9]+([\.-][a-z0-9]+))*$",$email) ){
// Bad Email
$es = "Bad Email Format";
} else {
//Good format query update goes here
}

[bretticus]

you can extract the domain name using a combination of substr and strpos to find the position of the @.

And if it is a valid domain, at what point do I update a database ? ANd if it isnt, do something else.

ummm...use if statements 😃 Not sure what you mean here?? Maybe..

if (//email checks out okay)
{
       if (//get the proper whois output or i use gethostbyname() and it gives me an ip.)
{
   //stick it in the database.
}
}

[bretticus]

Also, you could use a shell function to 'dig -t mx domain' to get the mx (mail exchanger or mail server for that domain.) Then using the socket code (port 25), init a smtp transaction to the server: "rcpt to: [e-mail]". If "user unknown" or some other variant (or language) comes back, you will know it is bogus.

[slimjim]

Ok take your code first, No idea on how you get the domain part after the @
But also how would I add that to the code below I already have.
The Part I do have does make sure if it is in right format. Now I need to check to make sure people do not put in bogus domains.
Can you add your socket code into the below code once. Something has to work. No biggie if you don't I can keep reading on this issue.

$email = $_POST['email']; 
if(!eregi("^[a-z0-9]+([_\.-][a-z0-9]+)*". "@([a-z0-9]+([.-][a-z0-9]+))*$",$email) ){ 
// Bad Email show error
$es = "Bad Email Format"; 
} else { 
//Good format query update goes here 
}