We have found 3 bugs in roundcube:
you can only choose New Zealand GMT + 12:00 (NZST), but at the moment we are in GMT+13:00 (NZDT) so messages show the incorrect data on them if you set to New Zealand.
email. It should send the HELO of the machine which its coming from (ie HELO webmail.example.com - the machines hostname) not HELO localhost (HELO localhost should only be used when sending to localhost)
headers in reverse order (ie the Recieved Headers are at the bottom etc) (can be reproduced using dbmail imap server, but it doesn't happen on dovecott imap server)
Thanks Craig Whitmore Orcon Internet