Open Settings on the app’s main window and go to "Data Storage" > "Backup & Restore".

You can back up your accounts and folder settings, and optionally include the app’s settings.

The backup file is optionally encrypted with a password (of your choosing) which will be required to restore. Make sure to remember or write down this password.

Aqua Mail lets you backup & restore from cloud-based storage (Google Drive, OneDrive, and Dropbox are supported) or the phone's internal storage. The files are stored in "backup/AquaMail" pre-Android 11 or in your Downloads folder For Android 11 and higher.

Actual messages are not archived or restored. The app will re-sync them from the mail server(s).