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e-mail validation

I've been looking for a simple way of checking that a string is an e-mail
address. I don't need to check if the address exists, just if the format of
the string matches. There seem to be lots of different methods, can someone
suggest which is the best, with justification. I'm not looking for total
accuracy, I'd much rather let a few false positives through than get any
false negatives.

Many thanks
Jul 16 '05 #1
4 3820
Hello,

On 08/20/2003 07:14 PM, Geoff Soper wrote:
I've been looking for a simple way of checking that a string is an e-mail
address. I don't need to check if the address exists, just if the format of
the string matches. There seem to be lots of different methods, can someone
suggest which is the best, with justification. I'm not looking for total
accuracy, I'd much rather let a few false positives through than get any
false negatives.


You may want to check these classes:
http://www.phpclasses.org/emailvalidation
It has basic regular expression based validation if you do not want to
use the DNS or SMTP server based validation.

http://www.phpclasses.org/formsgeneration
Also regular expression based validation integrated with forms
generation and validation on the client side using Javascript and on the
server side using the class itself.
--

Regards,
Manuel Lemos

Free ready to use OOP components written in PHP
http://www.phpclasses.org/

Jul 16 '05 #2
> I've been looking for a simple way of checking that a string is an e-mail
address. I don't need to check if the address exists, just if the format of the string matches. There seem to be lots of different methods, can someone suggest which is the best, with justification. I'm not looking for total
accuracy, I'd much rather let a few false positives through than get any
false negatives.

you could use the following regexp for a quick solution with preg_match().
regexp:
'/^([\._a-zA-Z0-9-]{1,}){1}@{1}([a-zA-Z0-9-]{1,}){1}\.{1}([a-zA-Z]{1,3}){1}$
/'

yours, dreamguard.
Jul 16 '05 #3

"Geoff Soper" <ne***********@alphaworks.co.uk> wrote in message
news:3f*********************@news.dial.pipex.com.. .
I've been looking for a simple way of checking that a string is an e-mail
address. I don't need to check if the address exists, just if the format of the string matches. There seem to be lots of different methods, can someone suggest which is the best, with justification. I'm not looking for total
accuracy, I'd much rather let a few false positives through than get any
false negatives.

Many thanks


This is a PHP version of a JavaScript I found that performs syntax checking
on an email address... There is sufficient remarks in it to let you know the
checks that it does - you just pass it an email address and it will return
"TRUE" or "FALSE" pending if its valid or not. Note, I return my TRUE and
FALSE as a string (ie, inside double quotes) and not as a CONSTANT or INT.

Function (and an example of usage) is below:
function verifyEmail($emailAddress)
{
// Return "TRUE" if we believe $email is a valid email address,
// else return "FALSE"

// First - make sure it has an @ sign and ensure that each side
// of the @ sign has enough characters to be a valid address
$pos = strpos($emailAddress, "@");
if ($pos === false) { // note: three equal signs
return("FALSE");
}

list($email, $domain)=explode("@", $emailAddress);
if( (strlen($email)==0) || (strlen($domain)<2) )
{ return("FALSE"); }

// make sure the top level of the domain name is no less than
// two characters, and no greater than four characters in order
// to allow .uk, .com, .info, .net etc...
$domains=explode(".", $domain);

// Make sure the right side of the @ sign (the domain) is made
// up of at least two subdomains (ie @xyz.com and not just @com)
if(count($domains)>1)
{ $tld=array_pop($domains);
// Make sure the top level domain is NOT less than 2 char in length
// and not greater than 4 char in length
if( (strlen($tld)<2) || (strlen($tld)>4) )
{ return("FALSE"); }
}
return("TRUE");
}

$e**********@large.com;
if(verifyEmail($example)=="FALSE")
{
die("Email address $example is NOT valid.");
}
print("<hr>Email address $example is believed to be fine and dandy.<hr>");
Jul 16 '05 #4
"Geoff Soper" <ne***********@alphaworks.co.uk> wrote in message
news:<3f*********************@news.dial.pipex.com> ...

I've been looking for a simple way of checking that a string is an e-mail
address. I don't need to check if the address exists, just if the format of
the string matches. There seem to be lots of different methods, can someone
suggest which is the best, with justification.


It all depends... For example, do you want to support the "user at
domain dot com" syntax? A slightly less wicked one: do you want to
treat '"Geoff Soper" <ne***********@alphaworks.co.uk>' as a valid
e-mail address or do you only want to deal with the 'news.20-08-
03@alphaworks.co.uk' part?

Cheers,
NC
Jul 16 '05 #5

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