If you are in a “working environment” and you are working for a large corporation, your IT department should be doing this for you using the archiving / retenti

If you are in a “working environment” and you are working for a large corporation, your IT department should be doing this for you using the archiving / retention systems built into G Suite / Office 365 / whatever mail server you’re using. If you aren’t using an IT-managed system, look into the best way to create backups of your email service and store those backups with your regular backups. Google offers “Google Takeout” or there are SaaS services that will do this for you, e.g. Backupify. Other email services have similar features.