I was working a new project where any ppl can join if they have a valid e-mail address.So i have to chk the e-mail address.Then i just found this function below.

function check_email_address($email)
{
// First, we check that there’s one @ symbol, and that the lengths are right
if (!ereg(“^[^@]{1,64}@[^@]{1,255}$”, $email))
{
// Email invalid because wrong number of characters in one section, or wrong number of @ symbols.
return false; }

// Split it into sections to make life easier $email_array = explode(“@”, $email); $local_array = explode(“.”, $email_array[0]);
for ($i = 0; $i < sizeof($local_array); $i++)
{ if(!ereg(“^(([A-Za-z0-9!#$%&'*+/=?^_`{|}~-][A-Za-z0-9!#$%&'*+/=?^_`{|}~\.-]{0,63})|(\”[^(\\|\")]{0,62}\”))$”, $local_array[$i])) { return false; } }

if (!ereg(“^\[?[0-9\.]+\]?$”, $email_array[1]))
{
// Check if domain is IP. If not, it should be valid domain name $domain_array = explode(“.”, $email_array[1]);
if (sizeof($domain_array) < 2)
{ return false;
// Not enough parts to domain
}

for ($i = 0; $i < sizeof($domain_array); $i++)
{ if (!ereg(“^(([A-Za-z0-9][A-Za-z0-9-]{0,61}[A-Za-z0-9])|([A-Za-z0-9]+))$”, $domain_array[$i]))
{ return false; } } }

return true; }