Invalid address: return even on successfully sent e-mail
This is because of the absence of $message_text['from'];
In SMTP module smtp.module.inc line 74-85 there is hack that handles the absence of 'Reply-To' by setting it to $message['from'] which is also absent, consequently 'Reply-To' will be empty hence throwing the error Invalid address:.
add $message_text['from'] = 'your from address' this will solve the issue.