Best Email Security Software: 11 Options Compared

Most cyber attacks on small businesses still start with an email. A fake invoice, a lookalike supplier, a login page that isn't what it seems. The right tool catches them before anyone clicks.

The eleven tools below are listed alphabetically and in no particular order, from straightforward filters to platforms used by large enterprises. Every description comes from the vendor's own site, read this week. For the human side of the problem, read my steps to protect your company from phishing.

Email security software at a glance

In the free plan column, Yes means the tool's own site names a free plan, a free version, a free app or an open source edition. Trial only means a time-limited trial. Not stated means the pages I read named neither, even where there's a button inviting you to try it.

Tool	Type	Good for	Free plan
Abnormal AI	Behavioral AI for email, identity and AI security	Business email compromise	Not stated
Check Point Harmony Email	Inbox protection from Check Point	Microsoft 365 and Google Workspace	Trial only
Hornetsecurity	Microsoft 365 security	Microsoft 365 add-on protection	Trial only
IRONSCALES	AI email security platform	Phishing remediation and training	Not stated
Libraesva	Email security for AI-driven threats	Layered, AI-powered protection	Trial only
Material Security	Protection for Google Workspace and Microsoft 365	Account takeover and data exposure	Not stated
Mimecast	Human risk management and advanced email security	Email plus human risk	Not stated
Paubox	HIPAA compliant email and email security	Healthcare email	Not stated
Proofpoint	AI email security and core email protection	Large enterprises	Not stated
SpamTitan	Email security, protection and filtering	Schools, SMBs and MSPs	Not stated
Trustifi	AI-powered email security services	Encryption and outbound protection	Not stated

Eleven email security tools to consider

Abnormal AI

Best for: Organisations worried about business email compromise, impersonation and QR code attacks that slip past older filters.

Check Point Harmony Email

Best for: Teams on Microsoft 365 or Google Workspace that want prevention-first email security from a big firewall vendor.

Hornetsecurity

Best for: Microsoft 365 users who want email security, encryption, signatures and archiving added on top of the platform.

IRONSCALES

Best for: Lean IT teams and MSPs that want faster phishing remediation plus real-world phishing simulations and training.

Libraesva

Best for: European businesses that want AI-powered, layered email protection they can trial for a month before deciding.

Material Security

Best for: Cloud-first companies that want to contain account takeovers and data exposure across Google Workspace or Microsoft 365.

Mimecast

Best for: Mid-size and larger organisations that want advanced email security alongside tools for managing human risk.

Paubox

Best for: US healthcare organisations that need HIPAA compliant email, inbound threat protection and secure forms.

Proofpoint

Best for: Large organisations that want email protection via API or gateway plus DMARC, data loss and insider threat tools.

SpamTitan

Best for: Small businesses, schools and managed service providers that want straightforward email filtering with easy M365 setup.

Trustifi

Best for: Firms in legal, healthcare and public sector work that want inbound and outbound shields plus email encryption and data loss prevention.

Stop people sending email as you

The National Cyber Security Centre (NCSC) guidance on email security tells organisations to configure anti-spoofing controls, starting with a DMARC policy of none, then creating SPF and DKIM records, before moving on to marking and rejecting spoof emails.

A security tool guards your inbox, but it's those records that stop criminals sending mail that looks like it came from your domain. Do both.

Filter, Microsoft 365 add-on or AI platform?

Simple filters block spam, malware and known phishing, and suit small businesses and schools. Microsoft 365 and Google Workspace add-ons sit on top of the platform you already use, adding protection, encryption and archiving. AI-based platforms learn normal behaviour and flag impersonation, unusual requests and account takeovers that older filters miss.

Many businesses start with a filter and add an AI layer once they've seen a convincing impersonation attempt. Don't wait for a near miss if you handle supplier payments by email.

Questions to ask before you choose

1. Does it work by API, as a gateway or both?
2. How does it handle impersonation and invoice fraud?
3. Can staff report suspicious emails with one click?
4. What does it do about account takeovers?
5. Does it include training or phishing simulations?
6. How much tuning does it need after setup?

Features that matter more than they look

• Impersonation detection. Catches fake bosses and suppliers.
• One-click reporting. Staff flag suspicious mail in seconds.
• Automatic clean-up. Bad emails pulled from every inbox at once.
• Encryption. Sensitive mail protected on the way out.

Small business starting point

If you're a small team, don't overcomplicate it. Get the DNS records right, add a filter that suits your email platform, and run a short phishing awareness session. That'll cover most of the risk, and it's a sensible base to build on.

Do you make email security software? Tool makers can ask to be considered for a featured place on this list.

My plain advice on choosing email security software

Start with the basics before you buy anything. Turn on multi-factor sign-in, set up SPF, DKIM and DMARC, and train people to pause on any email asking for a change of bank details. Then choose a tool to catch what slips through.

When you trial a product, look at what it catches that your current setup missed, not the size of its threat dashboard. My guide to why emails get marked as spam is useful for the deliverability side once your records are in place.

Frequently asked questions

What is email security software?

It protects email from spam, malware, phishing and impersonation, and often adds encryption, data loss prevention and archiving.

Is there free email security software?

None of the tools on this list named a free plan on the pages I read. Several offer free trials, so check the table.

Do I need email security if I use Microsoft 365?

Microsoft 365 includes protection, but many businesses add a layer focused on phishing and impersonation.

What are SPF, DKIM and DMARC?

They're DNS records that help receiving servers check an email really came from your domain. The NCSC recommends setting them up.

What is business email compromise?

It's a scam where criminals impersonate a colleague, supplier or boss by email to trick someone into handing over data or making a transfer.

Can email security tools stop account takeovers?

Some tools here specifically look for compromised accounts. Check the good for column.