Try SysTools Gmail Backup tool to export Gmail emails, contacts, calendars and Google drive storage files into multiple file formats. This tool also takes the backup of Google Docs / Spreadsheets / Slides / Images. For more info, visit its official website: https://www.systoolsgroup.com/gmail-backup.html
imapsync - Console-based utility for migrating IMAP mailboxes.
Gmvault - Backup the emails in your Gmail account.
Got Your Back - Got Your Back (GYB) is a command line tool that backs up and restores your Gmail account.
Cryoserver - Cryoserver is an all-in-one email archiving solution that empowers you to preserve your email in a tamper-evident archive, making you transform your data into a useful archive for everyday use.
Softaken Gmail Backup Pro - Backup Gmail emails to local PC with Softaken Gmail Backup Tool
Mail Backup X - Your one stop mail backup and archiving tool for Mac.