Open Gmail in a web browser
Click the gear icon
Select See all settings
Open the Forwarding and POP/IMAP tab
Enable POP or IMAP if needed
Use Google Takeout to export Gmail data
Go to takeout.google.com
Sign in to your Google account
Deselect all products
Select Mail
Choose the export format
Choose delivery method
Create the export
Download the backup file when ready
Save the backup file to a secure location
Use an email client like Outlook or Thunderbird to sync Gmail via IMAP
Copy important emails to local folders in the email client
Save attachments separately if needed
Repeat backups regularly
Verify the backup files after download