MailStore - MailStore Home - A 100% free single-private-user desktop solution
Mimecast Gateway - Mimecast Gateway is a SaaS-based email security solution that uses sophisticated, multi-layered detection engines and intelligence to protect email data and employees from malware, spam, advanced threats and zero-day attacks.
Got Your Back - Got Your Back (GYB) is a command line tool that backs up and restores your Gmail account.
dmarcian - Safeguard your email from abuse
SysTools Gmail Backup - Backup Gmail Emails, Contacts, Calendar, and Google Drive Storage File by SysTools Gmail Backup Solution
Hornetsecurity - Hornetsecurity offers you comprehensive, integrated managed e-mail security services.