If you use Thunderbird to connect to your email services, there's an addon called Import Export Tools that will create a nice HTML list of all emails currently in the box of interest, plus a folder of the emails themselves in a universal (Except Microsoft) .eml format. I do this once a week and put them in yearly folders, this allows me to easily search for emails, since I can usually remember the around-this-time frame of the email, even if I can't remember the exact date. https://addons.thunderbird.net/en-us/thunderbird/addon/importexporttools/