Please note, Saving an Email to PDF involves two APIs, i.e., Aspose.Email and Aspose.Words/Aspose.PDF. So, you have to use both APIs for the conversion. We have checked and saving to PDF by Aspose.Email is out of the scope. So, you have to first convert Email to MHTML and then either use Aspose.Words or Aspose.PDF to render MHTML to PDF. See the supported file formats by Aspose.Email, Aspose.Words and Aspose.PDF for your reference.