Cloud Email Security: Microsoft 365 & Google Workspace

Last updated: September 7, 2026

Cloud email security is no longer optional for any business that runs on Microsoft 365 or Google Workspace. Email is still where most attacks begin: phishing, business email compromise, account takeover, and a rising wave of AI-generated social engineering all arrive through the same channel your team lives in every day. The built-in filtering in your email platform is good, but it was never designed to catch the most targeted and evasive threats on its own.

That is the gap AegisAI closes, whether your company runs on Microsoft 365, Google Workspace, or both at once.

What is cloud email security?

Cloud email security is protection that is delivered from the cloud and integrated directly into your cloud email platform, rather than installed as on-premise hardware or bolted on as a gateway in front of your mail flow. A modern cloud email security platform connects to Microsoft 365 or Google Workspace through their APIs, analyzes messages for threats, and remediates anything malicious, all without changing how your email is routed.

The advantage is simple. Because it runs in the cloud and connects through an API, it deploys in minutes, adds no latency to your mail flow, and can act on threats even after a message has landed in the inbox. That last point is where cloud-native tools pull ahead of the older gateway model.

Why native email security is not enough on its own

Microsoft and Google both ship strong baseline protections, and they stop huge volumes of spam and commodity malware. The problem is the long tail: the low-volume, highly targeted attacks engineered specifically to slip past generic filters.

This gap is widening fast. In our own threat research, AI-generated phishing attacks grew 5x in 2025 and now slip past traditional filters at nearly double the rate of human-written email, reaching the inbox more than half the time. Against modern AI-generated attacks, native filtering is close to a coin flip.

These are the messages that cost companies real money. A convincing invoice from a spoofed vendor. A CEO impersonation asking finance to move funds. A phishing link that was clean at delivery and weaponized an hour later. Native filtering catches the obvious. It is the sophisticated, human-targeted attacks that get through, and those are exactly the ones that lead to a breach.

Effective email threat protection means adding a second, independent layer trained on precisely these threats: a distinct detection engine that catches what the first layer misses, rather than a duplicate of what your platform already does.

How AegisAI cloud email security works

A lot of email security was designed in the era of the secure email gateway. To deploy it, you rerouted your mail flow, changed your MX records, and pushed every message through a third party before it reached your users. That model made sense fifteen years ago. Today it adds latency, creates a single point of failure, and leaves you blind to anything that happens after a message reaches the inbox.

AegisAI takes a different approach. The company was founded by former Google security engineers who built the platform API-first from the ground up, rather than adapting a legacy gateway. We connect directly to Microsoft 365 and Google Workspace through their native APIs. There are no MX record changes, no mail rerouting, and no disruption to how your email already flows. You authorize the connection once through OAuth, and AegisAI begins analyzing messages in place, working alongside your platform's protections rather than in front of them.

The result is defense in depth without the operational drag. Your native controls keep doing what they do well, and AegisAI catches what slips past, then removes it automatically.

Cloud email security for Microsoft 365

AegisAI is built to work with Microsoft 365 natively through the Microsoft Graph API. We layer on top of Exchange Online Protection and Microsoft Defender for Office 365, adding a separate detection engine rather than duplicating what Microsoft already does.

Running two tools that catch the same obvious spam gives you very little. Running AegisAI alongside Microsoft gives you a second, independent set of eyes trained on the sophisticated, low-volume attacks that generic filtering tends to miss. Because we operate through the API, we can quarantine, remediate, and claw back malicious mail without you touching your Microsoft configuration or your mail flow.

For organizations consolidating on Microsoft 365 and asking whether the native security tier is enough on its own, AegisAI is the layer that turns "probably fine" into "covered."

Supplementing Microsoft 365 E3 and E5 with a third-party security layer

Microsoft 365 customers often ask whether upgrading to E5, or turning on the full Microsoft Defender for Office 365 Plan 2, is enough. For most organizations it gets you close, but not there.

E5 and Defender Plan 2 add attack simulation training, threat intelligence integration, and extended detection and response. They do not change the underlying detection model. Microsoft's filters are trained on the full volume of global email and tuned to stop threats at scale. They are not tuned for the targeted, low-volume attacks written to blend into your organization's normal traffic.

The gap AegisAI fills is the same at every Microsoft 365 license tier, because we run a separate detection engine built on behavioral and contextual signals instead of a second pass of the same filtering logic. Alongside E5, that protection is additive. Alongside E3, it covers the threat categories an E5 security upgrade is usually bought for: spear phishing, BEC, and account takeover.

If you are weighing an E3 to E5 upgrade mainly for security reasons, talk to us first. AegisAI may close the gap at a lower total cost.

Cloud email security for Google Workspace

If your organization runs on Gmail, AegisAI integrates directly through the Google Workspace APIs. Because the connection is API based, we see messages after your Google protections have already run, which means we are inspecting exactly the threats that made it through the first layer.

That post-delivery visibility is a real advantage. It lets AegisAI detect and remediate threats that only reveal themselves over time, such as a link that was safe at delivery and weaponized later, or an account takeover that unfolds across a series of otherwise unremarkable messages. When we identify a malicious message, we pull it from every affected inbox automatically, so a threat that reaches one user does not sit waiting in a hundred others.

Onboarding is a matter of connecting through OAuth and granting the right scopes. There is no agent to roll out and nothing changes for your users. Their inbox works exactly as before. The difference shows up in what gets pulled out of it.

Protecting Google Workspace from business email compromise

Business email compromise is one of the most expensive threats hitting Google Workspace environments, and one of the hardest for native filters to catch. A BEC attack needs no malicious link and no infected attachment. It is a convincing message from what appears to be a trusted sender, asking someone on your team to take a harmful action.

The common patterns are vendor impersonation (a spoofed invoice from a supplier your finance team recognizes), CEO fraud (an urgent wire request that appears to come from your CEO), and payroll diversion (an employee's direct deposit details changed through a convincing HR impersonation). None of them carry the payloads that signature-based filtering looks for.

AegisAI identifies BEC from behavioral and contextual signals rather than content alone. Is the sender's display name inconsistent with their actual domain? Does the request follow a pattern your organization has never seen? Is the urgency or tone out of character for this sender's history? Those questions take reasoning about context, and a rule set cannot answer them.

Google Workspace also has an attack surface that Microsoft 365 does not: the calendar. In a campaign we documented in September 2026, compromised Workspace mailboxes sent calendar invites that Google itself DKIM-signed. Gmail delivered them and auto-created the event with no click required. The link inside led to a signed remote monitoring and management (RMM) agent, which gives the attacker persistent control of the endpoint. AegisAI retracts the calendar entry as well as the email, because quarantining the message alone leaves the event in place.

Cloud email security vs the secure email gateway

The clearest way to understand the value of a cloud-native platform is to compare it to the secure email gateway it replaces.

For most mid-market and enterprise teams already standardized on Microsoft 365 or Google Workspace, the gateway is a legacy tax. Cloud-native email security removes it. If you are comparing vendors, our guide to evaluating API-based email security covers MX records, mail flow impact, and SIEM integration in detail.

How multi-agent AI detects threats that single classifiers miss

Most email security tools run a single detection model. One classifier scores each message and produces a verdict. That works for known threats with clear signatures. It works poorly against the attacks reaching your inbox today.

Social engineering does not always contain a malicious link or a known-bad attachment. Often the only signal is context: an unusual sender relationship, a request that is slightly out of pattern, a tone that does not match the person it claims to be from. A single classifier cannot hold all of that context at once.

AegisAI runs a team of specialized AI agents that reason together on each message, the way a group of security analysts would. One evaluates the sender relationship and communication history. Another analyzes language, intent, and behavioral signals. A third weighs the surrounding context across the thread. They compare their findings and reach a verdict together, in real time. That is how AegisAI flags a threat whose only tell is that it does not fit how your organization actually communicates.

It is also why AegisAI catches what Microsoft Defender and Google's built-in filters miss. They are optimized for high-volume, generic threats. AegisAI is optimized for the targeted, low-volume attacks engineered to look legitimate. The team that built it spent years on security infrastructure at Google and designed the system around multiple agents from day one.

Frequently asked questions

What is the difference between cloud email security and a secure email gateway?

A secure email gateway inspects mail at the perimeter before delivery and requires MX record changes to deploy. Cloud email security connects through your platform's API, deploys in minutes with no routing changes, and can remediate threats even after they reach the inbox.

Does AegisAI replace Microsoft Defender or Google's built-in protection?

No. AegisAI runs alongside your native protections as a separate detection layer. Your platform handles the baseline, and AegisAI catches the targeted threats that get through.

How long does deployment take?

Because AegisAI is API-native, most organizations connect in minutes through OAuth. There is no agent to install and no change to your mail flow.

Does AegisAI work for both Microsoft 365 and Google Workspace?

Yes. AegisAI protects Microsoft 365 through the Microsoft Graph API and Google Workspace through the Google Workspace APIs, from a single platform with the same detection engine on both.

Can I run the same platform to protect both Microsoft 365 and Google Workspace at the same time?

Yes. AegisAI connects to both through their respective APIs from a single platform, with the same detection engine on both environments. Organizations running a hybrid setup, or mid-migration from one platform to the other, get consistent protection across both without running two products.

How do I add email security on top of Microsoft 365 E3 or E5?

AegisAI connects to Microsoft 365 through the Microsoft Graph API and requires no change to your existing configuration or license tier. You authorize the connection through OAuth, and AegisAI begins analyzing messages alongside your existing Microsoft protections. There is no agent to install and no change to how your email flows. Most organizations connect in minutes.

How do I deploy email security for Google Workspace without changing MX records?

AegisAI integrates through the Google Workspace APIs directly, so your MX records stay exactly where they are. There is no rerouting of mail flow, no third-party relay, and no latency added to delivery. You grant the appropriate OAuth scopes, and AegisAI begins reading and acting on messages after your Google protections have already run.

How do I add a third-party security layer to Google Workspace without disrupting my current setup?

Because AegisAI connects through the Google Workspace APIs rather than sitting in your mail flow, adding it changes nothing your users experience. Their inbox works the same way. You gain a second detection layer operating on the threats Gmail's native filtering delivers, including links weaponized after a message has already reached the inbox.

How do I protect Google Workspace from business email compromise?

AegisAI detects BEC from behavioral and contextual signals: unusual sender relationships, out-of-pattern requests, and tone mismatches that carry none of the payloads signature-based filters look for. The section on protecting Google Workspace from business email compromise above walks through how this works.

How is agentic AI applied to email security?

AegisAI uses a multi-agent architecture in which specialized AI agents reason together on each message rather than running a single classifier. One agent evaluates sender relationships and communication history. Another analyzes language and behavioral signals. A third weighs contextual signals from the surrounding thread. Together they reach a verdict the way a group of security analysts would, which is how AegisAI catches threats whose only tell is that they do not fit how your organization normally communicates.

See what your current stack is letting through

Whether you standardize on Google Workspace, run entirely on Microsoft 365, or manage both at once, AegisAI protects all of it from one platform with the same fast, non-disruptive deployment.

You should not have to choose your email security based on which productivity suite you happen to run. Reach out for a demo and we will show you exactly what your current setup is missing.