Forwarding well-looking emails from the SMTP server

We have developped an algorithm on PHP that intercepts the emails coming as answers to previously sent emails by us. The algorithm already knows the addressees to whom send the emails: what we have to do is to forward emails received on our imap server, add a text and a logo and send them via phpmailer plugin. The previous developper had some problem but he's available to explain and illustrate what he did. I already have a fixed small budget for this project, but we know that is a very little coding task.