Ran a recovery program (Kroll Ontrack) on a Windows 7 PC and recovered many, many emails. Almost all of them open in my Windows 10 mail client (and Thunderbird), except for a handful from this March. They look like the image above, or even some are blank. There are not empty files, though, as they have file sized ranging from a few KB to 2 MB. Incidentally, these are the most important emails. Is this a sign of a .eml being encrypted? Or is it something else? Although Thunderbird says they're not. Perhaps these are attachments that aren't loading right? But why only March? And all of the other emails have perfectly fine images, docs, PDFs, etc. Just these handful from March.
I tried using Ontrack's email repair tool, but first I had to convert the .eml to .pst, then recover. This did not work, as the emails were still gibberish, just in a new file format.
Any help would be great.