Fast Facts
- Company HQ: Greenville, South Carolina, United States
- Founded: 2000
- Number of Employees: 50-100 employees as of May 2025
- Ownership: Private
- Investment: Raised $5 million in total funding over two rounds, with the latest being a $5 million Series A round from Ballast Point Ventures on March 5, 2020. Additional funding from Lighter Capital in a mezzanine debt round (amount undisclosed).
Our Analysis
Unsolicited sales emails pose a significant challenge for professionals. The rise of generative AI has driven a surge in targeted spam, produced at scale to overwhelm business inboxes.
The email security market is highly competitive, yet many solutions are ill-equipped to address this issue. Designed primarily to block malicious threats like malware, they often fail to filter non-malicious but disruptive spam.
Mailprotector takes a distinct approach to email security. Its flagship product, Shield, is a cloud-based email security solution that combines zero trust filtering with machine learning to manage inbox noise and protect against common threats. Tailored for managed service providers (MSPs) and smaller organizations, Shield prioritizes user-driven email management and rapid deployment.
Mailprotector describes its solution as “radically different” from other email security providers.
Let’s explore this further:
A ‘Circle of Trust’ for Email
Mailprotector’s primary differentiator is its machine learning-driven “circle of trust” model, which builds a trusted network for each user’s inbox. This system evaluates email patterns and sender relationships to identify trustworthy messages. Emails from unknown senders are automatically routed to a junk folder, with users able to add or remove senders from their circle as needed.
Mailprotector frames this as a “zero trust” email strategy. This approach assumes unknown emails are risky by default, permitting only messages from verified senders. Essentially, Mailprotector acts as a noise filtration system, eliminating irrelevant or potentially harmful emails while ensuring access to critical communications. Shield’s dynamic banner notifies users of new senders, prompting them to trust or silence them, training the filter through user actions.
This model differs from traditional threat detection, which relies on signature-based or rule-based filtering. Mailprotector instead uses a dynamic, relationship-driven system. By continuously learning from user interactions, the platform can refine its filtering and become more effective over time.
For professionals inundated with spam, this customization offers a clear advantage, allowing them to prioritize high-value tasks. The platform’s interface enhances this control, making it accessible to users without advanced technical knowledge.
Effectiveness Against Email Threats
Mailprotector’s zero trust framework is particularly effective against advanced email threats like phishing, as well as high-volume spam and sales campaigns, which typically originate from unverified senders.
Leading providers like Abnormal Security and Proofpoint, while strong in targeted threat detection, can struggle with low-sophistication, high-volume spam that slips through their filters.
This positions Mailprotector as a potential alternative for organizations where either spam volume or advanced email attacks from unknown senders is the primary concern. Its ability to block these emails without frequent rule adjustments improves efficiency and reduces administrative effort.
Potential Cautions
Mailprotector’s zero trust model works by building a circle of trust based on known email contacts. Messages from unknown email senders are blocked or moved to spam by default.
However, something to be aware of is the risk of email account compromise. If one of your trusted contacts is compromised and the attacker is able to mimic the tone of voice of the original account holder, this might not be flagged by Mailprotector as a malicious email. As such any fraudulent attachments such as fake invoices sent by a compromised trusted sender would not be blocked.
Any malicious URLs or attachments (containing viruses or harmful materials) would be blocked as Shield automatically blocks dangerous attachments, even if the account is compromised.
We highly recommend implementing and enforcing multi-factor authentication to secure against business email compromise.
Tailored for MSPs
Mailprotector is purpose-built for the MSP community, addressing the needs of providers managing email security for multiple clients. Spam and phishing emails consistently challenge MSP clients, consuming valuable time and resources. Shield’s automated filtering and zero trust model, which treats unknown senders as untrustworthy, is designed to address these issues.
The solution prioritizes streamlined deployment and user-focused email controls to reduce management overhead for MSPs serving diverse client environments. Shield Pro’s Bundler feature further supports MSP clients by summarizing non-critical emails, enhancing inbox management.
Market Position
Mailprotector is a trusted brand in the MSP community, operating as a pure-play email security vendor for 25 years. While not a billion dollar market leader, it holds a strong reputation as a reliable, trusted partner for MSPs.
Use Cases
- Blocking high-volume spam: Shield’s zero trust model routes emails from unverified senders to a junk folder, targeting high-volume spam and sales campaigns that disrupt small to medium-sized businesses. This focuses on spam reduction in markets where advanced threat detection is less prioritized.
- Enabling MSP email security management: Shield automates spam and phishing filtering across client environments with a setup process designed for quick deployment and integration with Microsoft 365 to address its filtering limitations. This supports MSPs managing multiple clients by reducing administrative tasks.
- Supporting regulatory compliance: Shield enables secure email and file transfers without additional apps, with Lockbox securing sensitive emails via multi-factor authentication, facilitating compliance with regulations like HIPAA or GDPR in sectors such as finance and healthcare.
- Enhancing email management: Shield’s “circle of trust” model, adjusted via New Sender Review to trust or silence senders, and VIP Pass for immediate delivery of designated senders, filters emails based on job relevance. This targets businesses aiming to reduce inbox clutter.
- Providing email security visibility: Shield’s Email Security Briefing delivers scheduled dashboard reports on email activity and security actions, while Spotlight enables message search across the email stack. This addresses MSPs and clients needing centralized visibility into email security and message tracking.
The Interface
Strengths
- Zero trust email filtering: Shield’s “circle of trust” model uses machine learning to route unverified emails to a junk folder, with New Sender Review notifying users to trust or silence first-time senders and Shield Control enabling risk level adjustments. The Heads-Up Display provides real-time, color-coded security insights (green for trusted, red for risky) with one-click X-ray access for message analysis, designed to reduce spam and phishing for MSPs and smaller organizations.
- MSP-focused design: Shield automates spam and phishing filtering for managed service providers, with a deployment process avoiding MX record changes and integration with Microsoft 365 to address its junk filtering gaps, targeting simplified management across multiple client environments.
- Productivity features: Shield Pro’s Bundler consolidates non-critical emails (e.g., newsletters) into scheduled summaries, and the VIP Pass allows immediate delivery for designated senders after threat checks, designed to help MSP clients prioritize critical communications.
- Privacy and security enhancements: Shield’s Spy Tracker Blocking removes pixel trackers from emails, Burner Addresses enable temporary email aliases, and Lockbox secures sensitive emails with multi-factor authentication, aiming to protect user privacy and sensitive data in MSP client environments.
Cautions
- Account compromise risk: Mailprotector is designed to block threats from unknown senders, but cannot currently secure against malicious email messages sent from trusted senders that have been compromised where the language and tone used in the compromised account matches the original sender.
- Niche market focus: Designed for MSPs and smaller organizations, Shield may not address the complex security needs of larger enterprises. The service is also focussed on the US and Canada market, where 98% of its customers are based.
- Dependence on user engagement: Shield’s filtering relies on user actions, such as trusting or silencing senders, to train the system, which may require consistent interaction, particularly for non-technical users.
Conclusion
Mailprotector’s Shield product offers a zero trust, user-driven email security solution tailored for managed service providers and smaller organizations. Designed to filter high-volume spam and phishing while supporting compliance and inbox management, it prioritizes simplicity and MSP scalability.
