Most lists of GreatHorn alternatives are lists of email security products, and for a straight email replacement that is the right place to look. Proofpoint, Mimecast, Microsoft Defender for Office 365, Barracuda, Cisco Secure Email and Check Point’s Avanan come up again and again. But if the reason you are re-evaluating is that attackers now reach your people on their phones, none of those products closes that gap on its own. This guide separates the two decisions, compares the realistic options on criteria that matter, and shows how to test each one before you sign.

SmishAlert

smishalert.com

Extend Visibility Beyond Email

SmishAlert helps security teams collect and analyze suspicious mobile messages, correlate reports, and identify coordinated social engineering campaigns.

Explore SmishAlert

TL;DR

If you need a like-for-like email replacement, shortlist Microsoft Defender for Office 365, Proofpoint, Mimecast, Cisco Secure Email, Barracuda or Check Point (Avanan), and choose by architecture and governance needs.
Email alternatives address email-delivered threats. They do not give you visibility into SMS, iMessage or WhatsApp attacks aimed at employees, customers or members.
Treat a mobile messaging layer as a separate evaluation, with its own pilot tests: reporting speed, campaign correlation, evidence export and SIEM integration.
SmishAlert is built for that second decision. It sits beside whichever email platform you choose and covers employees, executives, customers, members and students.
Request quotes using identical user counts, channels, retention and integrations. Public review sites rarely publish enterprise pricing.

What the GreatHorn alternatives lists actually compare
Email security alternatives, compared by fit
What no email replacement will fix
Adding a mobile messaging layer
How to run a pilot that tells you something
Questions to put to every vendor
See it on your own threat model
FAQ
Sources

What the GreatHorn alternatives lists actually compare

GreatHorn is a cloud email security platform. Gartner Peer Insights describes it as software that protects organizations from email threats through continuous monitoring, threat detection and automated response. Its listed alternatives start with Proofpoint Threat Protection, Check Point Email Security and Mimecast Advanced Email Security. TrustRadius groups Avanan, Microsoft Exchange, Proofpoint, Mimecast, Barracuda, Cisco and Sophos in the same neighborhood.

The pattern matters. Every one of these comparisons is built around the mailbox. They measure phishing and malware detection, attachment and URL handling, data loss prevention, continuity and Microsoft 365 or Google Workspace integration. That is a legitimate category with real differences between vendors. It is also a category that ends where email ends.

So the first question is not “which vendor?” but “what gap are we trying to close?”

Email replacement: you want better detection, lower analyst overhead, a different deployment model or a consolidated contract.
Channel coverage: you want to see and act on social engineering that never touches a mailbox.

Many security teams need both. They are different purchases with different tests.

Email security alternatives, compared by fit

The table below summarizes how the most commonly surfaced options differ in positioning. It is a starting point, not a verdict: capabilities change by license tier, and you should confirm details with each vendor.

Option	Typical positioning	Best fit	Covers SMS or mobile messaging?
Microsoft Defender for Office 365	API-integrated protection inside Microsoft 365	Organizations standardized on Microsoft 365	No, email and Microsoft collaboration content
Proofpoint	Secure email gateway with a broad governance suite	Large enterprises with DLP, encryption and archiving requirements	No, email-delivered threats
Mimecast	Secure email gateway with continuity and archiving	Teams that value continuity and layered email controls	No, email-delivered threats
Cisco Secure Email	Gateway filtering with malware and DLP controls	Environments already built on Cisco	No, email-delivered threats
Barracuda	Email protection with a mid-market footprint	Lean IT teams wanting bundled controls	No, email-delivered threats
Check Point (Avanan)	API-based cloud email security	Teams that want post-delivery detection without changing MX records	No, email and connected SaaS

The architectural split is worth understanding. One 2026 comparison points out that Proofpoint and Mimecast are secure email gateways that sit in front of mail flow, while Microsoft Defender is API-integrated. That difference affects deployment effort, how quickly messages are evaluated and what you can remediate after delivery.

Ratings and price signals

Review sites give a rough sense of market sentiment. On the Gartner Peer Insights alternatives page, Proofpoint showed 4.7 out of 5 from 1,473 ratings, Mimecast 4.5 from 806, Barracuda 4.5 from 505 and Microsoft Defender for Office 365 4.4 from 254 at the time of our research. Ratings and counts move, so recheck them before you rely on them.

Vendor ratings and review counts comparison

Price is harder. PeerSpot reports one user example of roughly $92,000 a year for Proofpoint, while Cisco and Mimecast pricing varies by environment, model and components. Treat that as one buyer’s experience, not a quote. The practical rule: send every vendor the same requirements, including user count, channels, retention, integrations, support tier and deployment model, and compare like with like.

How to choose among the email options

Microsoft 365 is the center of gravity: start with Microsoft Defender for Office 365 and ask what the add-ons cost.
Governance, archiving and continuity drive the decision: Proofpoint and Mimecast are the usual finalists.
Your network and security stack is Cisco: Cisco Secure Email fits naturally.
You want API-based deployment with minimal mail-flow change: look at Check Point’s Avanan and the Microsoft-native option.

If you also want a local team to manage email protection and monitoring for a small organization, email security monitoring services are one way to cover the conventional email layer while you plan the rest of your stack.

What no email replacement will fix

Here is the problem with treating a GreatHorn replacement as a complete answer. Attackers who fail to get through your email controls move the conversation to a phone. An executive impersonation that starts as a text, a payroll change request sent over iMessage, or a credential harvesting link delivered by SMS never crosses your gateway. Your email telemetry is blind to it, and so is your awareness program unless employees know where to report it.

Industry reporting on the Smishing Triad describes campaigns impersonating HR, delivery services, Microsoft 365 and Okta, aimed at credential and one-time-password theft, sometimes followed by voice phishing. These examples are useful for designing tests. They are not a prevalence estimate, and we do not present them as one.

The same reporting treats the message as the first stage of an attack chain. Credential theft can be followed by anomalous access, MFA manipulation or a phone call. That means messaging telemetry has to connect to identity, endpoint, fraud and incident response workflows, or it becomes one more isolated inbox of reports.

For a deeper look at why the two channels behave differently, see our breakdown of smishing versus phishing for security teams and how SOCs correlate email gateway signals with SMS threats.

Why blocking centrally is hard

Academic work on SMS phishing explains why this is not just “email security for phones.” The 2025 IMC paper, Fishing for Smishing, mines public user reports and shows how fragmented the reporting landscape is. Carrier and government reporting services are regional, users are often unaware of them, and metadata is limited. Users also report benign messages.

The implications for a buyer are practical:

Collection has to be structured, so a report carries the sender, URL, user and device context.
Analyst review has to be built in, because a report is not a confirmed incident.
Correlation matters more than blocking one link, because campaigns span sender IDs, URLs and follow-on channels.
Privacy controls matter, because you are asking people to submit personal-device messages.

Adding a mobile messaging layer

A dedicated messaging layer is the fourth option in the shortlist: not a replacement for your email platform, but the control that covers what the email platform cannot see. SmishAlert is built for this role. It helps organizations detect, investigate and respond to social engineering delivered through SMS, iMessage, WhatsApp and other mobile messaging channels.

Two deployment models

Employee and executive protection. SmishAlert can be deployed to employees and high-risk users for mobile threat protection and reporting. The platform includes on-device iOS message filtering, Android and cross-channel reporting, and coverage for managed, BYOD and executive devices. If MDM is a sticking point, our guide to deploying mobile phishing protection without MDM explains the approach.

Customer, member and student reporting. Organizations can let customers, members, students and other constituents report suspicious texts without installing an app. This is a different use case from employee-only mobile threat defense and from an email gateway. It matters most for banks, credit unions, insurers, associations, colleges and K-12 districts, whose people are impersonated by scammers regardless of what the IT department controls. See how this works for banks and credit unions and for associations and benefits organizations.

Two deployment models — overview diagram

What it analyzes

SmishAlert analyzes reported messages and senders for executive impersonation, credential phishing, payroll fraud, payment scams, gift card fraud, brand impersonation and other messaging-based social engineering. Reports are correlated across an organization or user population to surface emerging attacks and give security teams actionable threat intelligence. Our write-up on phishing campaign correlation shows what two reports sharing one fingerprint can reveal, and live campaign examples show what the output looks like.

Audit-ready incident reporting and SIEM and API integration let the evidence flow into the tools your SOC already uses. For the workflow side, see how to turn SMS reports into SOC alerts.

Where each approach wins

Requirement	Email platform	SmishAlert
Block phishing and malware in mailboxes	Yes, this is the core job	Not its role
Email DLP, encryption, archiving, continuity	Varies by vendor	Not its role
Visibility into SMS, iMessage and WhatsApp attacks	No	Yes
Customer, member or student reporting without an app	No	Yes
Cross-user campaign correlation for text-based attacks	No	Yes
Executive impersonation by text	Only if it also arrives by email	Yes

The honest summary: SmishAlert is not a GreatHorn clone and does not try to be one. If your goal is to rip out one email platform and install another, choose among the email vendors above. If your goal is to cover the channel that sits outside every one of them, this is the layer to add.

How to run a pilot that tells you something

Whether you are testing an email alternative or a messaging layer, a pilot that only asks “was one message blocked?” tells you little. Build scenarios and measure operations.

Scenarios to include

Executive impersonation asking for a quick favor or gift cards
Payroll or payment change fraud
Credential harvesting, including shortened URLs
Brand impersonation of your own company or a vendor
Linkless social engineering, where there is no URL to scan
Coordinated follow-up across SMS, email, chat and voice

Metrics to capture

Time to report: how long from receipt to a submitted report, and how many steps the user needs.
Analyst triage time: minutes from report to verdict.
Campaign deduplication: whether ten reports of one campaign appear as one case.
Escalation quality: whether the case arrives with sender, URL, user, device and related reports attached.
Evidence export: whether you can hand the case to legal, HR or a regulator without reconstructing it.
Integration: whether alerts reach your SIEM, ticketing and identity tools.

SmishAlert is typically evaluated through a paid 30-day pilot, and the pilot fee is credited toward the first annual subscription. Licensing is annual and per user. Pricing is not published, so request a scoped proposal.

Questions to put to every vendor

Which channels do you inspect, and which do you only see if the threat also reaches email?
Can constituents report without installing software?
How are reports deduplicated and correlated, and across what time window?
What happens to reported personal messages: retention, access and deletion?
How does evidence get into our SIEM and incident response process?
What would a quote look like for our exact user count and retention requirements?

A vendor that answers these specifically is worth a pilot. One that answers with generalities probably has not built it.

See it on your own threat model

If your shortlist already has an email platform and your open question is what reaches employees and customers by text, we can scope a pilot around your scenarios. Start with the SmishAlert product overview, or read how companies protect employees from executive impersonation via text.

FAQ

What is the closest alternative to GreatHorn?

For email security, the closest matches are API-integrated and cloud-delivered products such as Microsoft Defender for Office 365 and Check Point’s Avanan. Gateway-based options like Proofpoint and Mimecast are also commonly shortlisted. Choose based on your mail platform, governance needs and how much deployment change you can accept.

Will a GreatHorn replacement protect against smishing?

Not by itself. Email security products inspect email-delivered threats, so a text message that never touches a mailbox is outside their view. Add a mobile messaging layer if employees, executives, customers or members are being targeted by text.

Can SmishAlert replace an email security platform?

No, and it is not designed to. It covers SMS, iMessage, WhatsApp and other mobile messaging channels, and complements whichever email platform you select. Most organizations run both.

How much do these tools cost?

Enterprise email security pricing is rarely published and varies by user count, components and deployment. One PeerSpot user cited roughly $92,000 a year for Proofpoint, which is a single example rather than a quote. SmishAlert does not publish pricing, so request a scoped proposal.

GreatHorn Alternatives: Email Security and Mobile Messaging