What Microsoft’s Email Security Data Reveals About the Threats in Your Inbox

Intro

Every day, your inbox faces a steady stream of attempts to trick you, scam you, or infect your device. The numbers behind those attempts are hard to come by, but Microsoft recently published a year’s worth of data from its Defender for Office 365 platform. The benchmarks cover what its filters see, block, and miss. While the data comes from enterprise customers, the patterns apply to anyone who uses email.

If you want to know what the real threats look like right now—and what you can do to avoid them—this is a good place to start.

What happened

In June 2026, Microsoft released a summary of its email security benchmarks covering a full year of scanning activity. The data is drawn from millions of emails processed by Microsoft Defender for Office 365. According to the company, the platform blocked more than 35 billion phishing emails and 70 billion spam messages over the year. More specifically:

  • Phishing and credential theft made up the largest share of malicious emails that reached users, despite filtering.
  • Malware attachments were less common but still present, often disguised as invoices, shipping notices, or voicemail messages.
  • Business email compromise (BEC) attempts—where attackers impersonate a trusted colleague or vendor—were a persistent threat that often bypassed traditional filters.

Microsoft also reported that attacks are becoming more sophisticated, using legitimate services like SharePoint, OneDrive, and even Google Drive to host malicious links. This makes it harder for automated filters to distinguish between a real file sharing request and a trap.

It is worth noting that these figures come from Microsoft’s own reporting, and there is no independent third-party verification. However, the trends align with broader industry research from Forrester and Gartner, which highlight email as the primary attack vector.

Why it matters

You do not need to work in a large organization to be targeted. Phishing, malware, and credential theft affect personal accounts just as often. The difference is that enterprise users have dedicated security teams and tools; most individuals have only their own habits and a basic email provider.

Understanding what attackers are doing right now helps you focus your defenses on the threats that are most likely to land in your inbox. For example, if you know that attackers are increasingly using fake sharing notifications from cloud services, you will be more skeptical when you receive a link to a document you did not ask for.

The Microsoft benchmark also shows that no filter is perfect. A small percentage of malicious emails get through even the best enterprise defenses. For everyday users, this means you cannot rely entirely on your email provider’s spam or phishing filter. You need to be able to spot a suspicious email yourself.

What readers can do

These steps are practical and do not require buying any software or changing your email provider.

Enable multi-factor authentication (MFA) on your email account. This is the single most effective measure. Even if an attacker steals your password, they cannot log in without the second factor. Most providers support MFA via an authenticator app, text message, or hardware token. Turn it on.

Use a unique, strong password for your email. Many account compromises happen because someone reused a password from a breached service. A password manager makes this easy.

Be skeptical of urgency. Attackers try to create panic—an unpaid invoice, a suspended account, a missed delivery. Pause. Do not click any link. Instead, go directly to the service’s website by typing the address yourself or using a bookmark.

Check the sender address carefully. Display names can be spoofed. Look at the actual email address, especially the domain. If it says “@gmai1.com” instead of “@gmail.com,” that is a red flag.

Hover over links before clicking. On a desktop, hover your mouse over a link to see the real destination in the status bar. If the URL looks odd or does not match the supposed sender, do not click.

Do not open unexpected attachments. If you receive an attachment you were not expecting—even from someone you know—verify with them through a separate channel. Their account might be compromised.

Consider using a dedicated email alias for sign-ups. Services like Apple’s Hide My Email, Fastmail masked email, or simple plus addressing in Gmail let you use a different address for each service. If one gets spammed or breached, your main inbox stays clean.

Sources

  • Microsoft official blog: Microsoft Defender email security benchmarking: Key insights from one year of data (June 15, 2026)
  • Microsoft blog: From transparency to action: What the latest Microsoft email security benchmark reveals (March 12, 2026)
  • Forrester study (commissioned by Microsoft): Total Economic Impact of Microsoft Security (June 2026) – note this study was funded by Microsoft
  • Gartner, Magic Quadrant for Email Security, 2025 – Gartner does not endorse any vendor; its reports are opinions based on its methodology