module to display e-mail from source

Does anyone know of any module which can display an e-mail from it's source? I mean, that it receives the mails source, and displays it as it is displayed in a webmail for example.. It should be able to hand HTML messages and attachments I searched the web and found nothing... I could take code from any PHP based Webmail and modify it a bit to do this, but maybe there's some existing module to do this.. thanks in advance, Juan