Synology Mail Server (MailPlus 20 Licenses)

The Mail Plus and Mail Plus Server packages allow your business to set up a secure, reliable, and private mail server, while giving your employees a modern mail client to receive and send messages. Furthermore, Mail Plus and Mail Plus Server are packages that can be installed on your Synology NAS, so there’s no need to rely on third-party services. Best of all, Mail Plus comes with 5 free accounts and flexible licensing plan to fit your needs.
A secure, private, and cost effective email solution
High-availability architecture maximizes the service uptime
Specially designed algorithm for high speed full-text search
Beautifully designed and intuitive mail client allows efficient email management
Cross-platform support on web client and dedicated mobile apps on Android/iOS