When you receive an email message from someone with Mac Mail, the free email application that Apple installs on every Mac, you might want to save a copy of the letter as a PDF file, so you can use it on a different computer. A PDF document looks the same no matter what computer it's opened on, using an application such as Adobe's free Adobe Reader or Apple's Preview.
Click "Mail" from the Dock on your Mac to launch the application.
Double-click an email message from the Mail application window to open it.
Click "Print" from the Mail menu. A box opens.
Click the "PDF" drop-down menu, then click the "Save as PDF" option.
Click a folder on your Mac where you want to save the email message to a PDF file. Type a name for the PDF in the "Save As" text box, then click "Save." The email message is converted to a PDF file in the folder you designated.