Depends on what you mean. There is a php class available to read and write in an excel format, but much simpler to write into a CSV file that is automatically read by excel.
As to reading an email in php, the data would have to be pretty standard in format or you would have a huge task finding and verifing what you need. Also, if you mean to read directly from a mail folder on a mail server, each mail server can store it's email in lots of ways and the web service selddom has permission to read from those folders. Qmail in Linux is fairly easy to extract from, but an exchange server would be difficult to impossible.
Post if you need more direction.
