What are some alternatives?
When comparing MailScanner and Rspamd, you can also consider the following products
Scrollout F1 - Scrollout is a free and easy to use anti-spam email gateway designed for Linux & Windows administrators without advanced email security experience.
SpamAssassin - Use this program to "Unspam" your mailbox(es).
Proxmox Mail Gateway - Protect mail server against spam, viruses and malware with Proxmox Mail Gateway security for businesses, government, education and non-profit organizations.
amavisd-new - amavisd-new is a high-performance interface between mailer (MTA) and content checkers: virus...
Altospam - Antispam and antivirus software on Cloud
Akamai - Akamai is the leading content delivery network (CDN) services provider for media and software delivery, and cloud security solutions.