blowdoof/PHP-Bounce-Handler
This class can be used to parse bounced message reports. It parses e-mail messages with multipart report content type formatted according to RFC 1892 and 1894 documents. If the bounce is not well formed, it also tries to extract some useful information. Exim is supported, partially. Please send bounce messages from your busted MTA, I'll extend the class to support them. It can extract the the address of the recipient that bounced as well the mail server response status code.