Sublime Security
Sublime Security protects Microsoft 365 and Google Workspace mailboxes with a detection engine whose rules are written in an open language that customers can read, change and share, and adds AI agents that investigate reported emails and write new detections when a fresh attack appears.
CyberReviewed Editorial Team · Updated · sublime.security
Company details
- Score
- 7.6/10Ranked 8 of 17
- Category
- Email security
- Founded
- 2019
- Headquarters
- Washington, D.C.
- Leadership
- Josh Kamdjou, co-founder and CEO
- Funding disclosed
- About $244 million, including a $150 million Series C in 2025
- Pricing
- Free for fewer than 100 mailboxes; $8.75 per mailbox per month for 250 to 2,499 mailboxes (AWS Marketplace)
- Best fit
- Security teams that want to see and tune why each email was blocked
Our take
Sublime suits security teams that want to read, tune and extend their email defenses rather than trust a sealed model, and its free tier lets a small company run it at no cost. Teams without someone to own detection tuning should expect a learning curve, though the AI agents now take on much of that work.
Scores by criterion
| Criterion | Score |
|---|---|
| Pricing transparency | 7.4 |
| Product scope and fit | 8.0 |
| Company durability | 7.8 |
| Evidence of adoption | 7.9 |
| Ease of adoption | 7.0 |
| Overall score (average of the five) | 7.6 |
Each criterion is defined on our methodology page.
Detection you can read
Sublime's detection engine is driven by a programmable rule language that customers can see and change, and the core platform can run in a customer's own cloud.5 Its rules can be shared, so customers learn from attacks seen elsewhere, which is how its founder pitched it at launch in 2023.6 In 2025 it added two AI agents: an Autonomous Security Analyst that investigates and triages reported emails, and an Autonomous Detection Engineer that writes and deploys new detections for a novel attack within hours.3 Its Enterprise plan also covers business email compromise, vendor fraud, spam and email bombs, with add-ons for email data loss prevention and phishing simulations.1
Free to start, priced per mailbox
Organizations protecting fewer than 100 mailboxes can use Sublime Core for free, and the core platform can be self-hosted for free at any scale.14 Larger customers can buy through AWS Marketplace, where the listing charges $8.75 per mailbox per month for 250 to 2,499 mailboxes and $6.25 per mailbox per month above 2,500.2 Sublime does not publish Enterprise prices on its own site.1
Two founders and a word-of-mouth climb
Sublime began in 2019 with Josh Kamdjou, a former offensive security specialist for the U.S. Department of Defense, and his co-founder Ian Thiel. It is based in Washington, D.C.58 It raised $9.8 million at general availability in 2023, a $60 million Series B led by IVP in December 2024 that brought total funding to $93.8 million, and a $150 million Series C led by Georgian in October 2025.643 The company says it has never sent a cold sales email or run a paid ad.5 It reported 100% growth in annual recurring revenue in the first half of 2025, said it had kept every enterprise customer it had signed, and counts Spotify, Snowflake, Zscaler and Anduril among them.3 Fast Company put it on its 2026 Most Innovative Companies list.7
How it compares with Abnormal AI and IRONSCALES
Abnormal AI also connects to Microsoft 365 and Google Workspace by API, but its verdicts come from behavioral models that the vendor trains and tunes. IRONSCALES pairs automated detection with crowdsourced reports from its customers' security teams and adds awareness training. Sublime sits closest to a security team's own tooling: every verdict can be traced to a rule that the team can read and change, and its free tier and self-hosted option make it the easiest of the three to trial.
Limits
Reviewers describe Sublime as powerful but not plug and play, and one wanted users to see every email held in their own quarantine. Enterprise prices are not public, and companies with between 100 and 250 mailboxes will need a quote, since the AWS Marketplace tiers start at 250.2
What customers say
Quoted word for word from public reviews on PeerSpot, retrieved October 22, 2026. Each quote links to the review or post it comes from.
Where it helps
Sublime Security has positively impacted our organization by allowing us to do much less manual phishing detection and email detection, and now we can automate a lot of that, freeing up a lot of our security team to do other work.
Overall, the auditability and the ability to evaluate the information in Sublime through various mechanisms made me very comfortable with setting these capabilities to auto-remediation.
Where it falls short
To improve Sublime Security, I think the learning curve is the primary concern; it is powerful, but it is not plug and play.
The ability for users to look at their own quarantine box needs improvement. So at the moment, it doesn't give you the ability to see every email that has been quarantined.
Sources
- Sublime Security, Plans and add-ons, accessed October 22, 2026
- AWS Marketplace, Sublime Email Security for Security Hub Extended, accessed October 22, 2026
- PR Newswire, Sublime Security raises $150M in Series C funding, October 28, 2025
- PR Newswire, Sublime Security secures $60 million in Series B funding, December 12, 2024
- Sublime Security, Sublime raises Series B, December 12, 2024
- TechCrunch, Sublime nabs $9.8M for an anti-phishing email security platform, February 21, 2023
- Fast Company, Most Innovative Companies 2026: Cyera, Chainguard, Horizon3.ai and Sublime Security
- Sublime Security, About us, accessed October 22, 2026
