RCPT To address extra < bracket

I am getting a lot of
Rcpt To: <"Nickname"

problems... The problem is that some gateways trigger on the first "<" and return "501"

I have solved it for now by commenting out the code so it looks like below (and it seems to work - at least better but without nicknames) - but this probably has a more profound issue underneath...

mimemail.inc

...
// it's a user object
if (is_object($address) && isset($address->mail)) {
//CO buggy < header return '"'.addslashes($address->name).'" <'.$address->mail.'>';
//added line below instead
return $address->mail;
...

rgds
C