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Cybersecurity · head to head

Mimecast vs Tenable Nessus

Mimecast logo

Mimecast

Cybersecurity

Email and collaboration security

From
$4/month
Rated
-
Full reviewWebsite
Tenable Nessus logo

Tenable Nessus

Cybersecurity

Network vulnerability scanner

From
Free
Rated
-
Full reviewWebsite

The short version

  • Only Tenable Nessus has a free tier, so it costs nothing to try first.
  • Each has a real cost: Mimecast no pricing is published for any product or plan, and every route ends at a quote or demo request; Tenable Nessus nessus Professional is $4,790 for one year, sold as an annual licence rather than a per scan or usage based fee
  • They diverge on capability: Mimecast covers Advanced threat detection, Tenable Nessus covers Network scanning.
  • Prices and features above were last checked on 30 August 2026.

Where they differ

Only the attributes on which Mimecast and Tenable Nessus actually diverge.

Attributes where Mimecast and Tenable Nessus differ
AttributeMimecastTenable Nessus
Starting price$4/monthFree
Free tierNoYes
PlatformsEmail, Cloud, CollaborationWindows, Linux, Macos, Cloud
Founded20032002

Identical on both: pricing model (subscription), user rating (Not yet rated), category (Cybersecurity).

What each one covers

Drawn from each product's published feature list. An absence here means we hold no record of it - not that the product lacks it.

Only in Mimecast

  • Advanced threat detection
  • Secure sharing
  • Email encryption
  • Message tracking
  • Email archiving
  • Legal hold
  • eDiscovery
  • Backup and recovery

Only in Tenable Nessus

  • Network scanning
  • Vulnerability detection
  • Configuration assessment
  • Malware detection
  • Compliance checking
  • Cloud security assessment
  • Mobile scanning
  • API access

Both cover

  • Jira
  • ServiceNow
  • SOC2 Type 2
  • ISO 27001
  • GDPR
  • Cloud deployment

What people use each for

The jobs each tool is most often brought in to do.

Mimecast

  • Email security filtering against phishing and targeted attacksnot Tenable Nessus
  • Email archiving, continuity and compliance for organisationsnot Tenable Nessus

Tenable Nessus

  • Vulnerability scanning of servers, network devices and web applicationsnot Mimecast
  • Configuration and compliance auditing against hardening benchmarksnot Mimecast
  • Point in time assessments by consultants and penetration testersnot Mimecast

Where each one falls short

Documented limitations, not opinions. Every one is a constraint you would hit in normal use.

Mimecast

  • No pricing is published for any product or plan, and every route ends at a quote or demo request
  • The platform is split into separately sold products for email security, awareness training, data protection and governance
  • Collaboration threat protection, DMARC analysis, incident response and email archiving are all further add ons on top of those

Tenable Nessus

  • Nessus Professional is $4,790 for one year, sold as an annual licence rather than a per scan or usage based fee
  • Support beyond the base entitlement costs an extra $400 per year for Advanced Support with 24x365 phone and chat access
  • The on demand training course is a separate $275 purchase for a single person for one year
  • Multi year discounts require paying for two or three years up front

Pricing, plan by plan

Mimecast

$4/month
  • Defender$4/month
    • Per user
    • Threat protection
    • Impersonation prevention
  • Archive$3/month
    • Email archiving
    • Legal hold
    • Search & recall
  • Unified$6/month
    • All Defender features
    • All Archive features
    • Backup

Tenable Nessus

Free
  • Nessus EssentialsFree
    • Up to 16 ips
    • Network scanning
    • Vulnerability assessment
  • Nessus Professional$2600/year
    • Unlimited targets
    • Enterprise features
    • Advanced analytics
  • Nessus Expert$5200/year
    • All Professional features
    • Cloud integration
    • Advanced reporting

Which should you pick?

Choose Mimecast if

  • You need advanced threat detection.
  • You work on Email, Cloud, Collaboration.
  • You also want secure sharing.
Mimecast review

Choose Tenable Nessus if

  • You need network scanning.
  • You want to start without paying.
  • You work on Windows, Linux, Macos, Cloud.
  • You also want vulnerability detection.
Tenable Nessus review

Questions people ask

Is Mimecast or Tenable Nessus better?
Neither clearly leads. Mimecast starts at $4/month and Tenable Nessus at Free, and user ratings are close enough to be indistinguishable. Choose on capability and platform support.
Which is cheaper, Mimecast or Tenable Nessus?
Tenable Nessus has a free tier; the other does not. Paid plans start at $4/month for Mimecast and Free for Tenable Nessus.
Does Mimecast or Tenable Nessus run on more platforms?
Mimecast runs on Email, Cloud, Collaboration. Tenable Nessus runs on Windows, Linux, Macos, Cloud.
Can I use Tenable Nessus for free?
Yes. Tenable Nessus has a free tier, so you can try it without paying. Mimecast starts at $4/month.
What is Mimecast best used for?
Mimecast is most often used for email security filtering against phishing and targeted attacks, email archiving, continuity and compliance for organisations. Of those, email security filtering against phishing and targeted attacks and email archiving, continuity and compliance for organisations are not what Tenable Nessus is typically brought in for.
What can Mimecast do that Tenable Nessus cannot?
Mimecast covers Advanced threat detection, Secure sharing, Email encryption, Message tracking. Tenable Nessus covers Network scanning, Vulnerability detection, Configuration assessment, Malware detection. Both handle Jira, ServiceNow, SOC2 Type 2, ISO 27001.

Answered from the vendors’ own pages

Mimecast: How much does Mimecast cost?

Mimecast does not publish pricing on its website. Customers must request a custom quote by contacting the sales team at +1 617 393 7000 or using the Get a Quote button.

Source
Tenable Nessus: What are the three Nessus offerings?

Nessus Essentials is a free introductory offering for educators, students, and career starters, limited to 16 IPs for scanning. Nessus Professional is designed for consultants and SMBs, providing unlimited IT scans across any location. Nessus Expert is the premium offering extending Professional with web application scanning, infrastructure-as-code scanning, and external attack surface assessment up to 5 domains.

Source
Mimecast: Is there a free trial of Mimecast?

Mimecast's trial and pricing options are not specified on the public website. Contact sales at +1 617 393 7000 or through their support portal at mimecastsupport.zendesk.com for trial availability.

Source
Tenable Nessus: What OS platforms does Nessus support?

Nessus runs on Debian/Kali Linux, Fedora, FreeBSD, Mac OS X, Red Hat/CentOS, SUSE Linux, Ubuntu, and various Windows versions including Server 2008, 2012, and Windows 7-10.

Source
Tenable Nessus: Can I use Nessus to scan third-party networks as a consultant?

Yes, Tenable permits you to use Nessus to scan third-party networks. Nessus Professional is ideal for consultants.

Source
Tenable Nessus: Can Nessus perform PCI external scanning?

Yes, you can use Nessus Professional to perform external network scans as required by the PCI DSS 11.2.2 requirement.

Source
Tenable Nessus: What additional features does Nessus Expert provide?

Web application scanning, which is dynamic application security testing (DAST) providing comprehensive visibility and insight into web application security issues; scanning code repositories for vulnerabilities; and assessing external attack surface with subdomain discovery.

Source
Tenable Nessus: What support options exist for Nessus Professional?

Standard Support includes software upgrades, patches, plugin access, and 24x7 support via chat and community portal. Advanced Support adds 24x7 phone access and committed SLAs: P1 less than 2 hours, P2 less than 4 hours, P3 less than 12 hours, P4 less than 24 hours.

Source
Tenable Nessus: How frequently are Nessus plugins updated?

Nessus plugins are updated daily, based on when vendors and security research sites publish new vulnerabilities.

Source
Tenable Nessus: How does licensing work in virtual machine environments?

Whether you are using Nessus in a physical or a virtual environment, the IP addresses or hosts that you are scanning from must be licensed.

Source
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