<pre>
<?php
function CheckEmail($Email, $Strict = FALSE) {
         if ($Strict === TRUE)  {
            $qtext = '[^\\x0d\\x22\\x5c\\x80-\\xff]';
            $dtext = '[^\\x0d\\x5b-\\x5d\\x80-\\xff]';
            $atom  = '[^\\x00-\\x20\\x22\\x28\\x29\\x2c\\x2e\\x3a-\\x3c\\x3e\\x40\\x5b-\\x5d\\x7f-\\xff]+';
            $pair  = '\\x5c[\\x00-\\x7f]'; 
            $domain_literal = "\\x5b($dtext|$pair)*\\x5d";
            $quoted_string  = "\\x22($qtext|$pair)*\\x22";
            $sub_domain     = "($atom|$domain_literal)";
            $word           = "($atom|$quoted_string)";
            $domain         = "$sub_domain(\\x2e$sub_domain)*";
            $local_part     = "$word(\\x2e$word)*";
 
            $expression     = "/^$local_part\\x40$domain$/D";
         }
         else {
        	$expression = '/^[-_a-z0-9\'+*$^&%=~!?{}]++(?:\.[-_a-z0-9\'+*$^&%=~!?{}]+)*+@(?:(?![-.])[-a-z0-9.]+(?<![-.])\.[a-z]{2,6}|\d{1,3}(?:\.\d{1,3}){3})(?::\d++)?$/iD';
	}
 
        return (bool) preg_match($expression, (string) $Email);
};

$email = 'tadjm-..-ahal@gmail.com';

var_dump(eregi("^[a-zA-Z0-9\._-]+@[a-zA-Z0-9\._-]+\.[a-zA-Z]{2,4}$",$email));
var_dump(preg_match('/^([a-z0-9])(([-a-z0-9._])*([a-z0-9]))*\@([a-z0-9])*(\.([a-z0-9])([-a-z0-9_-])([a-z0-9])+)*$/i',$email));
var_dump(CheckEmail($email,true));
var_dump(filter_var($email, FILTER_VALIDATE_EMAIL));

int(1)
int(1)
bool(false)
bool(false)