Addition ; real online e-mail validation as option for the user?

[seansan]

From devshed.com - looks good for people who want to have this. Online verification of the mail adresses. Very easy to implement.

We can add an option in config that defaults to 0 - so it is taken along development but does not trouble starting users

0 = off
1 = only DNS (MX record check)
2 = port check on remote mail server

function checkEmail($email) {
 // checks proper syntax
 if(preg_match("/^( [a-zA-Z0-9] )+( [a-zA-Z0-9\._-] )*@( [a-zA-Z0-9_-] )+( [a-zA-Z0-9\._-] +)+$/" , $email)) {
  // gets domain name
  list($username,$domain)=split('@',$email);
  // checks for if MX records in the DNS
  if(!checkdnsrr($domain, 'MX')) {
   return false;
  }
  // attempts a socket connection to mail server
  if(!fsockopen($domain,25,$errno,$errstr,30)) {
   return false;
  }
  return true;
 }
 return false;
}

[Lazlo]

This ticket can be closed, implemented in ​http://trac.roundcube.net/changeset/3042