You can download software from the Internet that will undelete (recover) permanently deleted email from your hard drive.
You can also hire someone who will come to your house who can bring flash drives over, recover said permanantly deleted emails to the flash drives, so you can print them out and not have them show up on your hard drive, but still save them for court in the future if need be.
You can also hire folks who can do this activity remotely via the Internet, and never even leave their home in Alabama (if that's where they live). Kinda neat. (The service, not necessarily their home in Alabama, on accounta' I never saw their home...

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You can also buy the software from Office Depot or wherever. One such program is called something "Mechanic". I bought one after the affair and recovered some deleted emails. Gave me peace of mind. One of the things that both the FWH and OW in my sitch said was "It wasn't like there were a bunch of emails going back and forth", which immediately made me think:
THERE WERE A BUNCH OF EMAILS GOING BACK AND FORTH!!!!!!
So I snooped.
I only found business stuff. It was worth it. Software cost about 40 bucks or so. The service call to have this done might be around 100 in my area. That would be worth it if I didn't have the skills to do it myself.
There are free trial offers on the internet, which are downloadable and will undelete many emails free of charge. Please know this process may take many hours to do, depending on the level of undelete you choose and the type of attachments involved. Videos take longer to undelete, of course.
Hope that helps.
To find these folks or software, Google "undelete email software", or "How do I undelete email". That will get you started. Computer services in the yellow pages for your local area will find you a geek who knows everything there is to know, and then some. I am, of course, just a woman who did this to find out what her husband was doing - and learned by the seat of her pants!!!!