I think I found a work around.
It seems to work. Although the way the email comes out of the system I don't know why it works.
In /program/steps/mail/sendmail.inc
Just after this line in the rcmail_mailto_format() function:
$mailto = trim(preg_replace($regexp, $replace, $mailto));
Add this code:
$mailtoarray=explode(',',$mailto);
for($x=0;$mailtoarray[$x];$x++)
{
$mailtoarray[$x]=trim($mailtoarray[$x]);
}
$mailto=implode(',',$mailtoarray);
Basically it strips the " " out of the email addresses. It seems to do some weird things with quote marks and adds them to the email address, but that doesn't appear to affect mail delivery for some reason. Be warned this could fuck everything up so be careful and make backups.