A Technical Point About Those Missing E-Mails

Here is how e-mail is typically stored: There are at least three hard drives where an e-mail is located: The sender, the server and the recipient. If there is more than one recipient of an e-mail the other recipient’s hard drives will also have copies. (Webmail is another story…)
Even supposedly-deleted data would still be on each of these hard drive – marked as deleted but still there – unless it has been overwritten. That is not as likely these days with very large-capacity hard drives. A data recovery effort would locate the e-mails or report why not. If the erasure was due to normal file overwriting, this would be apparent. And if it was due to intentional erasure, this would also be apparent.