Email Security Solutions That Don't Suck

Most "best email security" lists rank tools you can't deploy and skip the one decision that decides everything: gateway or API. Get that fork right and the shortlist writes itself. Get it wrong and you'll fight mail-flow tickets for a year.

Roughly 90% of breaches still start in the inbox, and business email compromise alone cost organizations more than $16.6 billion in 2024 according to the FBI's IC3 report.

So this is a roundup for people who have to pick something and live with it: 12 email security solutions, what each is good at, who it fits, and verified ratings from G2, Capterra, and Trustpilot so you're not trusting a vendor's own scoreboard.

TL;DR: Best Email Security Solutions By Fit

Gateway Or API: The Choice That Defines Your Shortlist

A secure email gateway (SEG) sits in front of your mail server. You change your MX record, route all mail through the gateway, and it filters known-bad content before delivery. That's the model Proofpoint, Mimecast, and SpamTitan were built on. It works, and it gives you outbound control, but it means a mail-flow change and it mostly sees mail at the perimeter.

Integrated cloud email security (ICES) is the newer model. Gartner coined the term in 2021 for tools that plug into Microsoft 365 or Google Workspace through API instead of rerouting mail. KnowBe4's breakdown puts it plainly: ICES connects in minutes, reads internal and post-delivery mail, and uses AI to catch social engineering that signature filters miss. IRONSCALES, Abnormal, Sublime, Check Point Harmony, and Graphus live here.

The market is moving. Vendor and analyst commentary on the shift runs high, with some sources citing 80% of organizations scaling back standalone SEG spend in favor of native Microsoft filtering plus an ICES layer on top. For most cloud-first shops in 2026, "native plus ICES" is the default, and a full gateway is the exception you justify, not the assumption you start with.

What Good Email Security Stops

Strip the marketing and every tool here fights the same five threats. Phishing, the broad net of fake login pages and malicious links. Business email compromise, the targeted impersonation that skips links entirely and just asks for money. Account takeover, where a stolen password turns a trusted internal mailbox into an attack tool. Malware and ransomware payloads hidden in attachments. And domain spoofing, where your brand gets forged to scam your own clients.

The foundation underneath all of it is authentication: SPF, DKIM, and DMARC. Those records tell receiving servers which mail is really yours, and DMARC set to reject stops attackers from spoofing your domain outright. No tool on this list replaces getting those right. They build on top of it.

The 12 Email Security Solutions, Ranked By Who They Fit

IRONSCALES

IRONSCALES is an API-based (ICES) platform built around AI phishing detection and a self-learning incident response engine. It deploys into Microsoft 365 in minutes, and end users get a one-click report button that feeds the model. For MSPs, the draw is the multi-tenant console and SOC-style automation that pulls malicious mail from every affected inbox at once. The trade-off: it layers on top of M365, so it assumes the basics are covered. Best for MSPs and mid-market teams that want strong phishing and BEC coverage without a gateway.

Ratings: G2 4.7/5 (53 reviews), Capterra 4.7/5 (7 reviews), no standalone Trustpilot page as of June 2026.

Check Point Harmony Email & Collaboration (formerly Avanan)

Harmony Email, the platform Check Point built from its 2021 Avanan acquisition, is an API-first ICES tool that scans mail after Microsoft's own layers but before the inbox. It reaches past email into Teams, Slack, and OneDrive, which matters as attacks move into collaboration apps. Onboarding is quick and multi-tenant, so it slots into MSP operations. The console can feel dense if all you want is email. Best for teams standardized on Microsoft 365 that want one vendor across email and SaaS collaboration.

Ratings: G2 4.6/5 (511 reviews), Capterra 4.8/5 (51 reviews, listed under Avanan), no standalone Trustpilot page as of June 2026.

Abnormal AI

Abnormal, now branded Abnormal AI, is behavioral-AI email security. It builds a baseline of how people in your org normally communicate, then flags messages that break the pattern, like the CEO who never wires money suddenly asking for a transfer. It's API-deployed, post-delivery, and strong specifically on BEC and account takeover, where there's no malicious link to catch. It's priced and positioned for mid-market and enterprise, not the smallest shops. Best for organizations whose biggest risk is social engineering, not spam.

Ratings: G2 4.8/5 (71 reviews), Capterra 4.9/5 (2 reviews), no standalone Trustpilot page as of June 2026.

Sublime Security

Sublime is the option for teams that want to see and control the detection logic. Its detection runs on an open, programmable rule language, so a security team can write, tune, and share rules instead of trusting a closed box. That transparency is rare in this category, and it's why SOC teams like it. The flip side: the power comes with a learning curve, and the smallest teams may not use it. Best for security-led orgs and MSP SOCs that want explainable, tunable detection.

Ratings: G2 4.9/5 (27 reviews), no Capterra listing as of June 2026, no standalone Trustpilot page as of June 2026.

Microsoft Defender for Office 365

If you're on Microsoft 365, you already own part of this. Defender for Office 365 builds on Exchange Online Protection with Safe Links, Safe Attachments, and anti-phishing tied into the wider Microsoft security graph. At the right license tier it's a credible baseline, and it costs nothing extra to switch on if you're already paying for it. The gap: it's the layer attackers test against most, so high-risk orgs usually add an ICES tool on top. Best as the foundation nearly everyone builds from.

Ratings: G2 4.5/5 (290 reviews), Capterra 4.6/5 (229 reviews), no standalone Trustpilot page as of June 2026.

Proofpoint Core Email Protection

Proofpoint is the enterprise incumbent: deep threat intelligence, granular policy control, data loss prevention, and the compliance tooling large regulated organizations need. It's gateway-rooted, so expect a mail-flow change and more configuration than an API tool. Reviewers consistently praise the protection and grumble about the admin interface and false positives that need manual release. Best for large enterprises that weight control and compliance depth over speed of setup.

Ratings: G2 4.6/5 (583 reviews), Capterra 4.2/5 (45 reviews), no standalone Trustpilot page as of June 2026.

Mimecast Advanced Email Security

Mimecast pairs a mature secure email gateway with archiving, continuity, and awareness training, a lot of email function under one roof. In March 2026 it added full API deployment and expanded integrations across hundreds of security vendors, a clear move to meet the ICES shift. Renewal pricing and aggressive default filtering are the common complaints. Best for organizations that want gateway-grade filtering plus archiving and continuity in a single contract.

Ratings: G2 4.3/5, Capterra 4.3/5, no standalone Trustpilot page as of June 2026.

Barracuda Email Protection

Barracuda is a long-running, MSP-friendly option that spans gateway filtering and API-based impersonation protection, with security awareness training and incident response in the bundle. It's straightforward to run and widely deployed across SMB and mid-market. The knocks: a dated interface in places and false positives reviewers find frustrating. Best for SMBs and MSPs that want broad, no-drama email protection from one familiar vendor.

Ratings: G2 4.4/5, Capterra 4.2/5 (11 reviews), no standalone Trustpilot page as of June 2026.

SpamTitan by TitanHQ

SpamTitan is a cloud secure email gateway aimed squarely at SMBs, MSPs, and resellers. TitanHQ reports a 99.99% spam catch rate and a 0.003% false positive rate, and the platform's multi-tenant management plus competitive per-mailbox pricing are why MSPs keep it on the shortlist. It's a gateway, so you're routing mail, and it leans more spam-and-malware than behavioral BEC. Best for MSPs and SMBs that want reliable filtering and clean multi-tenant billing.

Ratings: G2 4.6/5 (139 reviews), Capterra 4.6/5 (561 reviews); TitanHQ's Trustpilot page carries only a handful of reviews, too few for a meaningful score as of June 2026.

Graphus by Kaseya

Graphus is an API-based, automated phishing defense built for MSPs inside the Kaseya ecosystem. It deploys without a mail-flow change, learns trusted communication patterns, and auto-quarantines suspicious mail across an entire tenant. If you already run Kaseya, the integration is the selling point. If you don't, reviewers note the integrations beyond Kaseya are thin and the admin UI shows its age. Best for MSPs already standardized on Kaseya.

Ratings: G2 4.3/5 (72 reviews), Capterra 4.3/5 (27 reviews), no standalone Trustpilot page as of June 2026.

Coro

Coro folds email security into a broader, lightweight security platform aimed at lean IT teams and the MSPs that serve them. Instead of buying email, endpoint, and cloud security separately, you get modules under one console with one bill. Email protection is solid rather than the strongest in the category, so single-issue buyers chasing the hardest BEC may want a specialist. Best for SMBs and MSPs consolidating several security tools into one affordable platform.

Ratings: G2 4.7/5 (231 reviews), Capterra 4.6/5 (30 reviews), no standalone Trustpilot page as of June 2026.

Acronis Cyber Protect Cloud

Acronis is best known for backup, and Cyber Protect Cloud bundles email security with backup, disaster recovery, and endpoint protection in one MSP-oriented platform. For an MSP managing Microsoft 365 at scale, having email filtering and recovery under one vendor is the appeal, and Acronis was named best software in G2's Fall 2025 email security grid. Reviewers flag support quality and cost as the sticking points. Best for MSPs that want email protection inside an all-in-one data-protection platform.

Ratings: G2 4.7/5 (1,298 reviews), Capterra 4.1/5 (77 reviews), Trustpilot 4.5/5 (3,174 reviews).

Email Security Solutions Compared

How To Choose Without Regretting It

Skip the feature-checklist trap. Five questions get you to the right shortlist faster:

1. Gateway or API? If you're cloud-first on Microsoft 365 or Google Workspace, start with API/ICES and add a gateway only if you have a specific reason.
2. What's your real threat? Spam and malware are table stakes. If your risk is wire fraud and impersonation, weight behavioral AI (Abnormal, Sublime, IRONSCALES) over signature filtering.
3. One tenant or fifty? MSPs should treat multi-tenant management, automated onboarding, and per-mailbox billing as non-negotiable.
4. What do you already own? Defender for Office 365 ships with many M365 plans. Switch it on before you buy a second tool, then layer where it falls short.
5. What's the exit cost? A gateway means a mail-flow change to adopt and another to leave. API tools unplug cleanly. Factor switching cost in now.

Where Email Security Fits In Your Stack

Email security is one layer, not the whole job. The MSPs cutting cost without cutting protection are the ones who stopped buying every layer from a different vendor and started consolidating the operational core. The smarter play: run the email security tool that fits the client, then unify the rest of the stack so you're not paying eight vendors and stitching eight dashboards together.

That's the thinking behind OpenFrame, Flamingo's AI-native, all-in-one MSP and IT platform. It brings RMM, native PSA, and endpoint management into one system with no vendor lock-in, so the email security layer you choose plugs into a stack you control instead of one more silo.

The MSP security stack guide walks through the rest of those layers in order.

The complete MSP software guide maps 155 tools across 19 categories.

And the vendor lock-in breakdown shows what switching really costs.

Email Security FAQ

What is an email security solution?

An email security solution is software that filters inbound and outbound email to block phishing, malware, spam, spoofing, and business email compromise. Modern tools deploy as a gateway in front of your mail server or through an API that integrates directly with Microsoft 365 or Google Workspace.

What's the difference between a secure email gateway and ICES?

A secure email gateway reroutes your mail through an external filter before delivery using known-bad signatures. Integrated cloud email security connects through API, needs no mail-flow change, reads internal and post-delivery mail, and uses AI to catch behavioral threats like impersonation that signature filters miss.

Is Microsoft 365 email security enough on its own?

For low-risk environments, Microsoft Defender for Office 365 covers the basics. But it's the layer attackers test against most, so organizations facing targeted phishing or BEC typically add an ICES tool on top for behavioral detection and faster post-delivery remediation.

What is business email compromise?

Business email compromise is a scam where an attacker impersonates a trusted person, often a CEO or vendor, to trick someone into wiring money or sharing data. It rarely uses malicious links, which is why behavioral AI detects it better than signature-based filters.

How much do email security solutions cost?

Most email security tools price per mailbox per month, usually a few dollars, with discounts at volume and for MSP multi-tenant agreements. Gateway products and enterprise platforms often use custom quotes, so exact pricing typically takes a vendor conversation.

Do MSPs need different email security than businesses?

Yes. MSPs manage many client tenants at once, so they need multi-tenant dashboards, automated client onboarding, and per-mailbox billing. Tools like IRONSCALES, SpamTitan, Graphus, and Acronis build for that model, while single-tenant enterprise tools usually don't.

The best email security tool is the one your team will run correctly on day one, not the one with the longest feature list. Pick the deployment model first, match it to your real threat, and make sure whatever you choose plugs into a stack you own instead of one more vendor with your renewal date circled.