Alternatives to SpamBrella

Rspamd suits organizations operating their own mail systems and seeking gateway filtering with control over message data and custom rules.

Xeams suits organizations that want to run their own mail server or add filtering in front of an existing one.

Mailprotector

Mailprotector is aimed at managed service providers seeking email security and management products for their customers.

It suits hosting providers running mail at scale, especially those managing multiple customer domains.

It suits organizations, schools, churches, public offices and personal domain owners using standard SMTP servers for owned domains.