Anti-spam/virus for your Zimbra server


Key features integrated directly into the Zimbra experience

End-users self-manage white/black lists for their mailboxes

Admins can manage white/black lists for their entire domain


Start quickly & easily with cloud-based service

Mail Stronghold Cloud

NO SERVERS to buy. No software to license.

NO EXPERTISE needed. We will walk you through it.

NO WAITING. Be up and running the same day you order.

Contact Us!

Risk-free, affordable and personalized


30-day free trial followed by no-nonsense, flat-rate, per-user pricing

Start with no-cost Community plan, upgrade to Commercial later

Free, initial security consultation ensures we meet your needs

Compare Plans

Empower your team. Secure your teamwork.


START frustrating spam & viruses. STOP frustrating your team!

Enable everyone to block and unblock senders quickly and easily

Improve automated detection and prevention of unwanted messages


Secure. Proven. Guaranteed.


Designed for commercial & GOV compliance & regulatory standards

Processed more than 1 billion messages last year alone!

99.9% availability service level agreement (SLA) and satisfaction guarantee


Community Plan

  • In-bound email protection
  • DNS/URI blacklists (RTBL)
  • RFC 4408 support (SPF)
  • "Click" white listing
  • Grey listing
  • Denial of service mitigation
  • Ad at bottom of your website

Commercial Plan

Order Now!
Community features plus:
  • Anti-virus/spam scanning
  • Integrated black/white listing
  • Junk-folder spam quarantining
  • Out-bound content scanning
  • MX backup, and more, plus...
  • No ad at bottom of your website!

Custom Plan

Extended options:
  • S/MIME encryption gateway
  • Digital loss prevention (DLP)
  • Regulatory compliance design
  • Permanent archives/eDiscovery
  • Multi-tenant hosting integration
  • SSO & federated provisioning...


Zimbra (ZCS) version 6 or greater

Community/open source or commercial

Hosted or on-premises

After signup, change DNS MX record

Pro: install ZCS Mail Stronghold zimlet

Pro: route mail for outbound filtering option

Key Features

  • Secure, server-wide anti-spam/virus
  • 30-day no-obligation trial
  • 100% money-back guarantee
  • Convenient web Inbox integration
  • 99.9% SLA & 24x7 support
  • Proven: processing > 1 B emails/yr

Happy Testimonial

It's a great time-saver for our clients to be able to manage their own black/white lists from the Zimbra web client. Our spam and virus-related support tickets have decreased by more than 90% since we started service. Thanks, Mail Stronghold!

Jay - Senior Support Specialist
Customer since 2007, zMailCloud