How does way to scan within the PST files to find a particular text string

I’ve email printout with e-mail subject,sent out by the user who left our employ. His account was deleted and cannot be recovered. The user have left whole lot of PST files and we are hoping that he had saved this “sent” e-mail in one of them. The PST files are rather large and contain tons of folders each, so it’s kinda hard to go through each one finding this very specific Subject line. Is there any other way to scan within the PST files to find a particular text string, like this Subject line? Before I start googling this stuff, I thought someone might already been there/done that