Formating text sent via php application

Does anyone know how to control the formatting of a fax sent via a php application? Do i need to create the pdf first and then attach it? Or can i simply set the headers to html. I am having no luck getting the formatting right.

You can attach the file as a pdf to have trustfax send the pdf as a fax. You will need to make sure that the security identifiers are in the body of the email to ensure it is faxed from the proper account. If the identifiers are not in the body of the email or does not match an account, the fax will not be sent. You receive a reply from trustfax of the error.
here is a link on how to form the email properly: http://www.trustfax.com/guides/tf/tf_send.html#send_email