Validating an e-mail address

[vinyl-junkie]

Here's a slick way of validating an email address that someone passes you through your contact form:

if (eregi('^[a-zA-Z0-9._-]+@[a-zA-Z0-9._-]+\.([a-zA-Z]{2,4})$', $from)) {
   // code to send e-mail goes here
}

[marek_mar]

I'd change a few things.

PHP Code:

$email = trim($email);
if (preg_match('/^[a-z0-9._-]+@[a-z0-9._-]+\.([a-z]{2,4})$/i', $email)) {
   // code to send e-mail goes here
} 


[whizard]

Still, if you use this, understand that it is not infallible.(sp?) All it does is screen out someone from typing "dga;sfgharggnjg" into the email box. a@b.c would beat the script, as would 1@2.3. But, this script is still great at screening out some nonsense submissions.

Dan

[vinyl-junkie]

Originally Posted by whizard

a@b.c would beat the script, as would 1@2.3. But, this script is still great at screening out some nonsense submissions.

Nope. The regular expression says that there must be two to four characters after the @ symbol and that they must be alphabetic. I have this code in place in my contact form, and both your examples don't skirt my edits.

What might be interesting is using the Validate PEAR package. I haven't tried that, but it's supposed to somehow validate the domain as well as the email address.

[Velox Letum]

Originally Posted by vinyl-junkie

Nope. The regular expression says that there must be two to four characters after the @ symbol and that they must be alphabetic. I have this code in place in my contact form, and both your examples don't skirt my edits.

What might be interesting is using the Validate PEAR package. I haven't tried that, but it's supposed to somehow validate the domain as well as the email address.

Actually I believe it's 2-4 chars after the period for the TLD. 1@2.aa would work.

[vinyl-junkie]

Originally Posted by Velox Letum

Actually I believe it's 2-4 chars after the period for the TLD. 1@2.aa would work.

Proving once again that I'm terrible about interpreting regular expressions.

I just tested your example, and it does pass the edits in my contact form.

[Velox Letum]

There also needs to be a clause written into the regex to allow an additional period and 2-4 chars for domains such as .co.uk. I wrote the clause below:

PHP Code:

$email = trim($email); 
if (preg_match('/^[a-z0-9._-]+@[a-z0-9._-]+\.([a-z]{2,4})($|\.([a-z]{2,4})$)/i', $email)) { 
   // code to send e-mail goes here 
} 


[marek_mar]

It has worked with .co.uk before.

[Velox Letum]

It doesn't seem like it would, as a period is not allowed and co.uk is five characters. *shrug*

[marek_mar]

It's becouse the .co matches with the "[a-z0-9._-]+" part just after the @.
From:
email@site.co.uk
it matches like this:
[a-z0-9._-]+ => email
@ => @
[a-z0-9._-]+ => site.co
\. => .
([a-z]{2,4}) => uk

[gsnedders]

It'd probably be best to modify it to comply to RFC 2822, which is more or less the rules as to what is, and what isn't a valid email address. Examples are: user@example.com, User <user@example.com>

[Velox Letum]

Originally Posted by marek_mar

It's becouse the .co matches with the "[a-z0-9._-]+" part just after the @.
From:
email@site.co.uk
it matches like this:
[a-z0-9._-]+ => email
@ => @
[a-z0-9._-]+ => site.co
\. => .
([a-z]{2,4}) => uk

Ahh I see. My apologies.

[whizard]

Originally Posted by vinyl-junkie

Nope. The regular expression says that there must be two to four characters after the @ symbol and that they must be alphabetic. I have this code in place in my contact form, and both your examples don't skirt my edits.

Sorry, I misread the code.

Originally Posted by vinyl-junkie

Proving once again that I'm terrible about interpreting regular expressions.

Don't feel so bad

[Nikolis]

This is the expression I use to check against email address submissions...

PHP Code:

preg_match("/^(([^<>()[\]\\\\.,;:\s@\"]+(\.[^<>()[\]\\\\.,;:\s@\"]+)*)|(\"([^\"\\\\\r]|(\\\\[\w\W]))*\"))@((\[([0-9]{1,3}\.){3}[0-9]{1,3}\])|(([a-z\-0-9áàäçéèêñóòôöüæøå]+\.)+[a-z]{2,}))$/i", $_POST['email_address']) 


[Bill Posters]

Originally Posted by Error 404

It'd probably be best to modify it to comply to RFC 2822, which is more or less the rules as to what is, and what isn't a valid email address.

Fwiw…

http://www.regexlib.com/REDetails.aspx?regexp_id=711

^((?>[a-zA-Z\d!#$%&'*+\-/=?^_`{|}~]+\x20*|"((?=[\x01-\x7f])[^"\\]|\\[\x01-\x7f])*"\x20*)*(?<angle><))?((?!\.)(?>\.?[a-zA-Z\d!#$%&'*+\-/=?^_`{|}~]+)+|"((?=[\x01-\x7f])[^"\\]|\\[\x01-\x7f])*")@(((?!-)[a-zA-Z\d\-]+(?<!-)\.)+[a-zA-Z]{2,}|\[(((?(?<!\[)\.)(25[0-5]|2[0-4]\d|[01]?\d?\d)){4}|[a-zA-Z\d\-]*[a-zA-Z\d]:((?=[\x01-\x7f])[^\\\[\]]|\\[\x01-\x7f])+)\])(?(angle)>)$

http://www.regexlib.com/REDetails.aspx?regexp_id=26

^([a-zA-Z0-9_\-\.]+)@((\[[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.)|(([a-zA-Z0-9\-]+\.)+))([a-zA-Z]{2,4}|[0-9]{1,3})(\]?)$