Best Email Security for Microsoft 365 & Gmail (2026 Guide)

The best email security add-ons for Microsoft 365 & Google Workspace in 2026- Quick Answers:

Best overall for closing the training gap: Wizer Email Security (WES)
Best for vendor and supply-chain impersonation:  Abnormal AI
Best for crowdsourced detection: IRONSCALES
Best for enterprise policy depth: Mimecast

What Matters in an Email Security Add-On

• Catches BEC and vendor impersonation with no bad link or attachment to scan
• Deploys by API, no MX change, no disruption to mail flow
• Closes the loop with the person who got targeted, not just the message
• Doesn't just re-flag what your native filter already caught

If it just adds more noise on top of what Defender or Gmail already flags, it's not earning its place.

are the Top Add-Ons for 2026:

1. Wizer: Top choice for Simplicity + Closing the Loop

• API connection to Microsoft 365 or Google Workspace, no MX change
• Blocks phishing before it reaches an inbox
• Agentic MDR triages and investigates every report automatically
• Confirmed attacks get rebuilt as a phishing simulation and/or a short AI-generated training video that can be assigned to the rest of the org or  specific departments/people
• Dynamic employee risk score, recalculated with every attack and every reported attack
• Built in AI Assistant (like a ChatGPT email security expert that can generate reports for you, give you advice, bring you up to speed on most common recent attacks and so much more)

Great for: teams that want detection and training from one vendor instead of stitching two together.

2. Abnormal AI: Good for Vendor and Supply-Chain Impersonation

• Behavioral baselining across vendor and employee communication
• VendorBase flags a real vendor's account taken over and used against you
• Detection only — no built-in training, so a confirmed attack doesn't become a lesson for anyone
• API connection, no MX change

Avoid if: you don't have many third-party vendor relationships to protect, or you want training built in rather than a separate product.

3. IRONSCALES: Works for Crowdsourced Detection

• Adaptive AI plus threat intelligence crowdsourced from its own user base
• Built-in phishing simulation and awareness training, but as a bolted-on module rather than a single detection-to-training pipeline
• API connection, no MX change

Avoid if: you want a newer, more tightly integrated detection-to-training pipeline.

4. Mimecast: Choose for Enterprise Policy Depth

• Deep policy customization for teams that need granular control
• Training is a separate add-on module, not part of the core detection flow
• Gateway or API deployment — gateway requires an MX change

Avoid if: you need lightweight, fast deployment rather than enterprise policy control.

Comparison Table:

Why Wizer

• Detection and training built as one system, not bolted together
• Blocks phishing before it reaches an inbox, not just after someone reports it
• A confirmed attack becomes org-wide training automatically, same day
• No MX change, connects alongside Defender or Gmail, doesn't replace it

Using Gmail? Learn more here
Using Microsoft 365? Learn more here

How to Choose

Choose Abnormal AI if:

• you manage a lot of third-party vendor relationships and supply-chain risk is the priority

Choose IRONSCALES if:

• you want a longer track record and a larger existing user base behind the crowdsourced detection

Choose Mimecast if:

• you're already running a broader Mimecast stack and need granular policy control

Choose Wizer if:

• you want fast setup with no MX change
• you want autonomous triage 
• you want a built in AI Assistant (think of it like your personal ChatGPT for email security
• you want automatic risk scores given to your team based on number of attacks and reporting rates
• you want a confirmed attack to train your whole team automatically, not just get logged
• you want detection and training from one vendor instead of two

Final Take

The best email security add-on is the one that catches what your native filter structurally can't, not a longer feature list.

If it just re-flags what Defender or Gmail already caught, it's not adding coverage. If it doesn't do anything with the person who got targeted, it's not closing the loop.

How to Actually Use a Email Security Add-On:

• Confirm it deploys by API with no MX change, so it doesn't disrupt mail flow you depend on.
• Ask how long it takes to learn your organization's normal mail patterns, and what it does with low-confidence flags before then.
• Check what happens after a detection: human review, auto-quarantine, or — ideally — a loop back that inoculates the rest of the org against that same attack.
• Keep your native filter running underneath it, this is an added layer, not a replacement.
• Pair it with ongoing phishing simulations so the training side isn't a once-a-year afterthought.

Email security add-ons can close a real gap, but it's worth noting that the add-on alone isn't the whole program. Lasting protection comes from pairing detection with training and reporting, not from any one tool bolted on and left alone.

Below is a quick demo of Wizer Email Security
We hope this helps, the Wizer Team.