Spamihilator - The free Anti-Spam-Filter Spamihilator removes more than 98% of spam mails before they even get into your inbox.
Mimecast Gateway - Mimecast Gateway is a SaaS-based email security solution that uses sophisticated, multi-layered detection engines and intelligence to protect email data and employees from malware, spam, advanced threats and zero-day attacks.
SpamAssassin - Use this program to "Unspam" your mailbox(es).
dmarcian - Safeguard your email from abuse
Spam Reader - Spam Reader is a free anti-spam add-on for Microsoft Outlook.
Hornetsecurity - Hornetsecurity offers you comprehensive, integrated managed e-mail security services.