If you are looking for the most secure ways to backup your AWS emails then you can opt for the AWS WorkMail Migration Tool. This software allows you to backup or migrate your emails and other data from AWS WorkMail to other email servers or cloud-based email services. It also facilitates you to save your emails into multiple file formats such as PST, PDF, EML, MSG, CSV, etc. Moreover, users can also transfer their emails to Gmail, Office 365, IMAP, Gsuite, etc. To evaluate its functionality, you can download and run its free trial version.