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
Gmvault - Backup the emails in your Gmail account.
NeoCertified Secure Email - NeoCertified is a solution that provides secure email encryption for businesses and organizations across all industries, including healthcare, finance, legal, non-profit and education.
MailStore - MailStore Home - A 100% free single-private-user desktop solution
Virtru - Virtru is your data privacy force field, wrapping and protecting emails and files wherever they're shared. Easy-to-use data security software for business. People also askIs Virtru Hipaa compliant?
Got Your Back - Got Your Back (GYB) is a command line tool that backs up and restores your Gmail account.
Encyro - Use Encyro to send sensitive messages and files to your customers and service providers, including accountants, loan officers, health coaches, and others. Stay organized and forward documents from your mobile device.