Hi. Did you ever resolve this issue? If not, I'm going to post my query - My only issue with autoresponder is that it's sending the confirmation emails (to the user after they sign up), to my roundcube mail, instead of the user's email. So I guess I only have 1 out of the 3 issues you were experiencing.
Seems straight forward - correct where the post goes to, but I can't see at all if this is a roundcube issue or my php handler issue..