Few Years ago I wrote an email validator function for sites forms, one that I used until I found email address validator from Google Code.Enjoy the code by clicking the download now button.

[PHP]check_text_length($strEmailAddress, 3, 256)) {
return false;
}

// Split it into sections using last instance of “@”
$intAtSymbol = strrpos($strEmailAddress, ‘@’);
if ($intAtSymbol === false) {
// No “@” symbol in email.
return false;
}
$arrEmailAddress[0] = substr($strEmailAddress, 0, $intAtSymbol);
$arrEmailAddress[1] = substr($strEmailAddress, $intAtSymbol + 1);

// Count the “@” symbols. Only one is allowed, except where
// contained in quote marks in the local part. Quickest way to
// check this is to remove anything in quotes. We also remove
// characters escaped with backslash, and the backslash
// character.
$arrTempAddress[0] = preg_replace(‘/./’
,”
,$arrEmailAddress[0]);
$arrTempAddress[0] = preg_replace(‘/”[^"]+”/’
,”
,$arrTempAddress[0]);
$arrTempAddress[1] = $arrEmailAddress[1];
$strTempAddress = $arrTempAddress[0] . $arrTempAddress[1];
// Then check – should be no “@” symbols.
if (strrpos($strTempAddress, ‘@’) !== false) {
// “@” symbol found
return false;
}

// Check local portion
if (!$this->check_local_portion($arrEmailAddress[0])) {
return false;
}

// Check domain portion
if (!$this->check_domain_portion($arrEmailAddress[1])) {
return false;
}

// If we’re still here, all checks above passed. Email is valid.
return true;

}

/**
* Checks email section before “@” symbol for validity
* @param strLocalPortion Text to be checked
* @return True if local portion is valid, false if not
*/
protected function check_local_portion($strLocalPortion) {
// Local portion can only be from 1 to 64 characters, inclusive.
// Please note that servers are encouraged to accept longer local
// parts than 64 characters.
if (!$this->check_text_length($strLocalPortion, 1, 64)) {
return false;
}
// Local portion must be:
// 1) a dot-atom (strings separated by periods)
// 2) a quoted string
// 3) an obsolete format string (combination of the above)
$arrLocalPortion = explode(‘.’, $strLocalPortion);
for ($i = 0, $max = sizeof($arrLocalPortion); $i < $max; $i++) { if (!preg_match(‘.^(‘ . ‘([A-Za-z0-9!#$%&'*+/=?^_`{|}~-]‘ . ‘[A-Za-z0-9!#$%&'*+/=?^_`{|}~-]{0,63})’ .’|’ . ‘(“[^\"]{0,62}”)’ .’)$.’ ,$arrLocalPortion[$i])) { return false; } } return true; } /** * Checks email section after “@” symbol for validity * @param strDomainPortion Text to be checked * @return True if domain portion is valid, false if not */ protected function check_domain_portion($strDomainPortion) { // Total domain can only be from 1 to 255 characters, inclusive if (!$this->check_text_length($strDomainPortion, 1, 255)) {
return false;
}
// Check if domain is IP, possibly enclosed in square brackets.
if (preg_match(‘/^(25[0-5]|2[0-4][0-9]|1[0-9][0-9]|[1-9]?[0-9])’
.’(.(25[0-5]|2[0-4][0-9]|1[0-9][0-9]|[1-9]?[0-9])){3}$/’
,$strDomainPortion) ||
preg_match(‘/^[(25[0-5]|2[0-4][0-9]|1[0-9][0-9]|[1-9]?[0-9])’
.’(.(25[0-5]|2[0-4][0-9]|1[0-9][0-9]|[1-9]?[0-9])){3}]$/’
,$strDomainPortion)) {
return true;
} else {
$arrDomainPortion = explode(‘.’, $strDomainPortion);
if (sizeof($arrDomainPortion) < 2) {
return false; // Not enough parts to domain
}
for ($i = 0, $max = sizeof($arrDomainPortion); $i < $max; $i++) { // Each portion must be between 1 and 63 characters, inclusive if (!$this->check_text_length($arrDomainPortion[$i], 1, 63)) {
return false;
}
if (!preg_match(‘/^(([A-Za-z0-9][A-Za-z0-9-]{0,61}[A-Za-z0-9])|’
.’([A-Za-z0-9]+))$/’, $arrDomainPortion[$i])) {
return false;
}
if ($i == $max – 1) { // TLD cannot be only numbers
if (strlen(preg_replace(‘/[0-9]/’, ”, $arrDomainPortion[$i])) <= 0) {
return false;
}
}
}
}
return true;
}

/**
* Check given text length is between defined bounds
* @param strText Text to be checked
* @param intMinimum Minimum acceptable length
* @param intMaximum Maximum acceptable length
* @return True if string is within bounds (inclusive), false if not
*/
protected function check_text_length($strText, $intMinimum, $intMaximum) {
// Minimum and maximum are both inclusive
$intTextLength = strlen($strText);
if (($intTextLength < $intMinimum) || ($intTextLength > $intMaximum)) {
return false;
} else {
return true;
}
}

}
[/PHP]