What are some alternatives?
EuropeanMX - Protects your company by blocking spam and virus before they reach your network.
SpamTitan - SpamTitan is an anti-spam email solution specifically developed to meet the demands of modern business. Delivering a spam detection rate over 99.9%
Hornetsecurity - Hornetsecurity offers you comprehensive, integrated managed e-mail security services.
Altospam - Antispam and antivirus software on Cloud
Symantec Email Security.cloud - Symantec Email Security.cloud provides always-on, inbound and outbound email security against malware, targeted attacks, and advanced threats
SpamAssassin - Use this program to "Unspam" your mailbox(es).