I am the power of attorney for my 77 year old relative who has dementia and is in an assisted living facility. Since I am also 77 and the only relative I am worried about the need to hire someone to care for my cousins financials, insurance, etc. if/when I become unable to continue. Our attorney wasn't able to come up with a solution and when I read the description of professionals who could handle dependents' affairs I was excited. Unfortunately I somehow deleted the email and can't seem to retrieve it.
You can also contact your e-mail service provider and ask them to search for an accidentally deleted e-mail. But if it's Comcast, don't bother; I just went through that and got nothing but worthless advice.
I would think that all e-mail servers store information on backup servers or what's more commonly referred to as the "cloud". Question is whether or not they'll bother. I think it would depend on your ISP.
Another good practice is to immediately print, save to your hard drive, or offline storage (disk, hard drive) all those kinds of e-mails with helpful information.
Regarding your email, there should be folders where your mail is stored. On my Macbook Pro, it is in the Mail function and a deleted email goes into my Trash folder. You can also go to YouTube and type in the search, "How to find a deleted email on a (list your type of device)" and an instructional video will probably exist to show you. Good luck!