How we make this list: we compare pricing pages, product documentation and public user reviews. Ratings come from G2, Capterra or Trustpilot, with the date we checked them.
Key takeaways
- Proofpoint is the closest enterprise grade replacement, with strong threat protection and large company support.
- Microsoft Defender for Office 365 is the simplest choice for teams already on Microsoft 365.
- SpamTitan and INKY give smaller businesses strong filtering at a more accessible price point.
- IRONSCALES stands out for phishing simulation and automated incident response.
- Most enterprise tools here use quote based pricing, so request a quote for your exact user count and mail volume.
Quick comparison
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The best Mimecast alternatives
Starting priceSee website
Free planFree trial
Proofpoint is the name most security teams compare first when they leave Mimecast. Its core email protection covers phishing, malware, business email compromise and impostor threats, with additional modules for archiving, data loss prevention and user awareness training. Large organizations value its reporting depth and its ability to enforce policy across thousands of mailboxes.
The trade off is cost and complexity. Pricing is quote based and typically sits at the premium end of this list, and smaller teams may find the admin console and policy options more than they need. If you run a regulated or large enterprise environment and want a proven, broad platform, Proofpoint is the safest shortlist pick. If you run a small business, start with SpamTitan or INKY and only move up if compliance demands it.
What we like- Comprehensive threat protection
- Strong enterprise controls
- Wide integration with security tools
Watch out for- Premium, quote based pricing
- Implementation can be complex for small teams
#2Microsoft Defender for Office 365
Best for: Microsoft 365 teams4.5/5 on
G2 (299 reviews, checked Oct 2026)
Visit microsoft.com
Starting priceSee website
Free planFree trial
For teams already on Microsoft 365, Defender for Office 365 is often the lowest friction alternative. It works inside Exchange Online and Teams, so there is no separate mail gateway to route through, and policies, quarantine and threat investigation live in the Microsoft security portal your admins already use. Safe Links and Safe Attachments add URL and file detonation checks that catch many attacks Mimecast users rely on a gateway for.
Licensing is the catch. The full feature set requires higher Microsoft 365 or Defender plans, and organizations on Google Workspace or mixed mail systems will get less value. Still, if your mail, identity and endpoints already live in Microsoft, Defender removes a vendor, simplifies support and keeps security close to the mailbox. Compare the total Microsoft licence cost, not just the Defender add on, before deciding.
What we like- Native Microsoft 365 integration
- No separate gateway to manage
- Strong phishing and malware controls
Watch out for- Best value only inside Microsoft licensing
- Advanced features sit in higher plans
#3SpamTitan
Best for: small business spam filtering4.5/5 on
G2 (199 reviews, checked Oct 2026)
Visit spamtitan.com
Starting priceSee website
Free planFree trial
SpamTitan earns its place through focus. It does spam, phishing and malware filtering well, with a cloud gateway that is quick to deploy and easy for a small IT team or MSP to manage. Reviewers on G2 repeatedly cite its filtering effectiveness, and that simplicity is a real benefit when you do not have a dedicated security team to tune complex policies.
What you give up is breadth. Archiving, advanced data loss prevention and large enterprise governance are thinner than Proofpoint or Mimecast, so SpamTitan fits best as a gateway replacement rather than a full security suite. For a small or mid sized business that mainly needs cleaner inboxes and fewer phishing clicks, it offers strong value without an enterprise sales cycle.
What we like- Effective spam and phishing filtering
- Straightforward setup
- Popular with small businesses and MSPs
Watch out for- Fewer enterprise extras than Proofpoint
- Reporting depth is more limited
#4IRONSCALES
Best for: phishing response automation4.7/5 on
G2 (65 reviews, checked Oct 2026)
Visit ironscales.com
Starting priceSee website
Free planFree trial
IRONSCALES approaches email security from the human layer. Its platform combines gateway style protection with phishing simulation, employee reporting tools and automated incident response that can remove a malicious message from every mailbox once one user reports it. That automation matters, because manual removal across hundreds of mailboxes is slow and error prone.
Reviewers praise its ease of use and value, even while noting it is not the cheapest option. The platform works well alongside Microsoft 365 or Google Workspace, and it suits teams that want to reduce analyst workload, not just block more spam. If your main pain is phishing that slips through filters and the time spent cleaning it up, IRONSCALES deserves a trial ahead of a broader gateway swap.
What we like- Automated phishing incident response
- Strong ease of use scores
- Phishing simulation and training built in
Watch out for- Pricing can feel high for very small teams
- Some features require higher tiers
#5INKY
Best for: small and mid sized phishing defense4.2/5 on
G2 (118 reviews, checked Oct 2026)
Visit inky.com
Starting priceSee website
Free planFree trial
INKY is built around a simple idea: show users why a message looks risky, right in the inbox. Its banner warnings explain spoofing, brand impersonation and other red flags in plain language, which helps staff make better decisions instead of blindly trusting a filter. That user facing clarity is why reviewers rate it highly for value among small and mid sized businesses.
Deployment is straightforward, and pricing is generally more accessible than enterprise gateways, though exact quotes depend on user count. The limitation is scope. INKY is a strong phishing and email security layer, not a full archiving or compliance platform, so regulated firms may need a second tool for retention. For an SMB leaving Mimecast for cost and simplicity, INKY is a practical first trial.
What we like- Cost effective for SMBs
- Clear phishing warnings in the inbox
- Easy deployment
Watch out for- Smaller feature set than enterprise suites
- Archiving and compliance tools are limited
Starting priceSee website
Free planNo
Abnormal Security takes a different technical route. Instead of relying mainly on signatures and rules, it builds behavioral profiles of senders, vendors and employees, then flags messages that break those patterns, even when they contain no known malware link. That approach is strong against business email compromise, vendor fraud and account takeover, which are the attacks that cause the largest losses.
Because it connects via API rather than changing mail flow, deployment avoids gateway disruption, which larger IT teams appreciate. Pricing is enterprise oriented and quote based, so it is not a budget pick. Choose Abnormal when sophisticated social engineering, not bulk spam, is your main risk, and when you have the budget for an AI led platform rather than a basic filter.
What we like- Behavioral AI that learns normal sender patterns
- Strong business email compromise detection
- API based, no gateway changes
Watch out for- Enterprise pricing
- Less suited to very small teams with simple needs
#7Barracuda Email Protection
Best for: all in one email security4.5/5 on
G2 (164 reviews, checked Oct 2026)
Visit barracuda.com
Starting priceSee website
Free planFree trial
Barracuda offers a broad, familiar alternative for teams that want email security, archiving and backup from one vendor family. Its email protection covers spam, phishing, malware and impersonation, and related Barracuda products can add archiving and data protection without a second vendor relationship. That breadth appeals to mid sized businesses and MSPs managing many clients.
The sprawl is also the drawback. Choosing between modules, plans and deployment options takes care, and costs rise as you add archiving or advanced threat features. Still, if you want a single vendor for several email related needs and a product line with a long support history, Barracuda is a credible Mimecast replacement to evaluate alongside Proofpoint.
What we like- Broad email security, backup and archiving options
- Long track record
- MSP friendly
Watch out for- Interface and module choices can feel sprawling
- Premium tiers add cost quickly
Starting priceSee website
Free planNo
Darktrace Email, part of the wider Darktrace platform, uses AI to learn how each user and organization normally communicates, then intervenes when a message deviates. That makes it strong against novel phishing, unusual language patterns and attacks that have no known signature. Security teams also value its explanations of why a message was held or allowed.
Cost is the consistent drawback in public reviews, with Darktrace frequently described as expensive compared with gateway alternatives. It fits best in organizations that already invest heavily in security and want AI detection as a layer, not in small businesses looking for a simple spam filter. Trial it if novel attacks are a real concern and budget allows, otherwise start with a simpler gateway.
What we like- AI that learns normal email behavior
- Strong detection of novel attacks
- Clear incident explanations
Watch out for- Frequently cited as expensive
- Best value in larger, security mature environments
How we chose
We compared pricing pages, product documentation and public reviews on G2, Capterra and Reddit, focusing on phishing and malware protection, business email compromise defense, Microsoft 365 and Google Workspace fit, archiving, admin effort and pricing transparency. We did not claim hands on testing. Most enterprise vendors here do not publish starting prices, so those tools are marked See website and require a quote for your user count.
Switching without breaking mail flow
Plan a Mimecast replacement like a mail migration, not a simple software swap. Start with a trial in monitor mode if the vendor offers it, so you can compare detection rates without changing delivery. Check archiving and retention first, because losing old mail or breaking legal hold is harder to fix than a missed spam message.
Next, map your policies: allow lists, blocked senders, attachment rules, URL rewriting and quarantine workflows all need to move across, and user training should explain any new banners or quarantine notices. Finally, run both systems in parallel for a short period where possible, measure false positives on legitimate mail, and only cut over Mimecast once the new tool proves itself on your real traffic. A rushed cutover on a Friday afternoon is how legitimate invoices end up in quarantine.
Frequently asked questions
What is the best overall Mimecast alternative?
Proofpoint is the closest enterprise replacement, while Microsoft Defender for Office 365 is best for Microsoft shops and SpamTitan or INKY are best for smaller budgets. The right pick depends on size, mail platform and compliance needs.
Is there a free Mimecast alternative?
No full enterprise gateway here is free, though several offer free trials. Defender is included in some Microsoft 365 plans, which can make it effectively free if you already pay for that licence.
Do these tools work with Google Workspace?
Yes, most gateway and API tools here support Google Workspace as well as Microsoft 365, though Defender is strongest inside Microsoft. Confirm Workspace support and any mail routing changes before buying.
Do I still need user training if I buy email security?
Yes. No filter catches every phishing message, so simulation and reporting tools from IRONSCALES or INKY remain valuable. Training reduces clicks on the messages that do get through.
How much do Mimecast alternatives cost?
Enterprise tools are usually quote based and can range from a few dollars per user per month for basic filtering to premium enterprise rates. Request quotes for the same user count and features to compare fairly.
Sources we checked (8)
- https://www.proofpoint.com
- https://www.microsoft.com/security/business/microsoft-365-defender
- https://www.spamtitan.com
- https://ironscales.com
- https://www.inky.com
- https://abnormalsecurity.com
- https://www.barracuda.com
- https://www.darktrace.com
Is your product missing or out of date?
We review this list regularly. Vendors can request a listing, send updated pricing or ask about featured placement.
Shihab Mia · Founder, Rankite
Shihab has 5+ years in B2B and SaaS SEO. He writes Rankite's software buying guides from pricing pages, documentation and public user reviews. More about Shihab.
Proofpoint
Abnormal Security
Darktrace Email