What are some alternatives?
Mailwasher - Over 8 million people use MailWasher as their spam filter
MailScanner - MailScanner is a open source email security system design for Linux-based email gateways.
Spamihilator - The free Anti-Spam-Filter Spamihilator removes more than 98% of spam mails before they even get into your inbox.
SpamAssassin - Use this program to "Unspam" your mailbox(es).
Kyte - India's first AI powered SMS inbox
Altospam - Antispam and antivirus software on Cloud