How to easily convert .p7s files to .pdf format.
Converting Digitally Signed Email Messages directly to Adobe Portable Document Format (.p7s to .pdf conversion) is not possible. There is, however, a simple workaround you can use. First, you will need to convert .p7s to .xps format. You can do that easily in Windows, and it only takes a few seconds.
Now that you have your .xps file, you can go ahead and use any available document conversion software or online conversion tools capable of converting .xps to .pdf format.
A dedicated XPS converter
A simple and efficient way to batch convert XPS or OXPS (OpenXPS) documents into PDF. The XPS-to-PDF supports JPEG, JPEG2000 and Flate image compression types along with output quality for PDF conversion.