In order to post images of the scanned letters, I need to convert the PDF scans to JPG files, one for each page, and my PDF viewer, Preview, will only convert one page of a PDF at a time. That would be a time-consuming task when you have hundreds of PDFs that may each be 5-6 pages or more, so I’m looking for a batch converter for my iMac. I’m narrowing it down to a couple, leaning toward one that automates the process and puts each letter bundle into its own folder:

PDF to JPG Pro: https://itunes.apple.com/us/app/pdf-to-jpg-pro-batch-pdf-to/id521554479?mt=12

Yes, it means I finally started creating pages for the letters.