What are some alternatives?
When comparing Scrollout F1 and SpamAssassin, you can also consider the following products
MailScanner - MailScanner is a open source email security system design for Linux-based email gateways.
Proxmox Mail Gateway - Protect mail server against spam, viruses and malware with Proxmox Mail Gateway security for businesses, government, education and non-profit organizations.
Mailwasher - Over 8 million people use MailWasher as their spam filter
BitNinja.io - BitNinja is the first integrated server defense network, can be installed within 1 minute on any...
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.