Business email security that’s built-in, not bolted on.

Phishing. Malware. Data leaks. All much harder to pull off when every inbox is secured by default. Protect your business with Proton Mail.

Get Proton Mail for Business Request a demo

What is email security?

Email security is the practice of protecting your inbox from becoming a victim of cyber threats. But not all practices are equal. Spam filtering alone won’t prevent phishing, malware, and account takeovers. Especially now when a single compromised account can put your whole network at risk. Businesses today need email cybersecurity that’s layered, organization-wide, and built-in. Not simply reactive to individual threats as they appear. It’s the best available way to keep conversations private, credentials secure, and teams moving. Here’s why that matters.

The importance of email security

Four in five small businesses have suffered a recent data breach. And that’s just one of the many cyber threats that SMBs face today. Phishing, impersonation, credential theft, malware, and account takeovers — can all start with just a single email.

Financial loss

A single incident can cost a small firm over $1 million.

Operational disruption

86%(new window) of cybersecurity incidents involved business disruption, spanning operational downtime, reputational damage, or both.

Compliance risk

GDPR regulatory fines can be set up to €10 million or 2% of annual global revenue for even minor infractions.(new window)

Reputation loss

The presence of a past breach significantly alters how consumers perceive a company.(new window)

4 common email cybersecurity threats for businesses

Most email attacks start with one convincing message — a request that feels routine, a sender that looks familiar, a moment when someone is busy or distracted. Attackers don’t need to break your systems if they can persuade someone to open the door for them. That’s why email remains the most common entry point for cyber incidents, and why some attack types are far more likely than others.

Below are the email threats businesses encounter most often. We’ll get into how they work, what they’re designed to exploit, and why traditional defences alone aren’t enough to stop them.

Phishing

What it is: Phishing emails are fake emails that appear to be from trusted sources, such as a team lead or vendor.

Why it works: These attacks could impersonate whoever you trust — a bank, a colleague, a vendor, or even a regular supplier.

What happens if it succeeds: Attackers can access emails, snoop on and steal confidential data, and even impersonate you to attack your customers and partners. More advanced phishing attacks can even lead directly to financial fraud.

Malware

What it is: Malware is malicious software designed to damage your systems and steal data. Ransomware is a devastating type of malware that encrypts your files until you pay the attackers.

Why it works: Malicious attachments often look like invoices, contracts, or shared documents — files employees open every day. Once opened, malware can run quietly in the background.

What happens if it succeeds: Without access to important data and systems, businesses can become paralyzed. Malware is spread through attachments and links.

Account takeover

What it is: Attackers gain access to emails and the ability to impersonate the account owner, usually by stealing credentials through phishing or reusing passwords exposed in previous data breaches.

Why it works: Once attackers log in as a real user, they don’t need to bypass security filters — they’re already inside. Their emails look legitimate because they are.

What happens if it succeeds: Compromised accounts can be used to spy on conversations, steal sensitive data, and send convincing attacks to colleagues, customers, and partners, amplifying the damage across your network.

Spoofing

What it is: Spoofing happens when attackers forge sender addresses to make emails appear to be from your business.

Why it works: Recipients trust familiar names and domains. Without proper email authentication, it’s difficult to tell whether an email truly came from your organization.

What happens if it succeeds: Spoofing allows businesses to demand payment from your partners using fraudulent invoices — damaging trust with partners and customers.

Data theft

What it is: Data theft, or data exfiltration, occurs when attackers use compromised accounts to steal sensitive business data such as customer information and financial records.

Why it works: Email often contains large volumes of regulated and confidential data, and compromised accounts can access it quietly over time.

What happens if it succeeds: In such scenarios, your business would violate regulatory frameworks such as GDPR and HIPAA, putting it at risk of heavy fines and potential lawsuits from affected parties.

Business email security best practices: A checklist

Set up email authentication

Protect your reputation by setting up SPF, DKIM, and DMARC protocols to prevent attackers from spoofing your domain. These protocols verify that emails are sent from your business and block fraudulent ones.

Enable multi-factor authentication

Enforce two-factor authentication (2FA) and single sign-on (SSO) across all accounts, and implement strong password policies. If an attacker successfully breaches an account, 2FA keeps them from accessing other systems.

Use an encrypted email service

End-to-end encryption protects the contents of all your messages so that only you and your intended recipients can read them which protects the data shared via business email from leaks. With an end-to-end encrypted business email service, like Proton Mail, not even your email provider has access to your data.

Create an incident response plan

An incident response plan outlines clear procedures for containment, investigation, and recovery when attacks happen. With a clear plan, your team will know exactly what to do, saving precious time and costs, while minimizing damage.

Conduct employee training

Train your team to recognize phishing attempts and to report suspicious emails. Awareness is key to spotting, avoiding, and preventing attacks.

Switch to Proton Mail, the most secure business email

Switching to secure email doesn’t need to be disruptive. With Proton Easy Switch, transferring your emails, calendars, and contacts is easy and risk-free.

Step 1

Switch from any email service: Proton Easy Switch works with Gmail, Outlook, Yahoo, and any IMAP email provider. All your data gets imported, while custom folders and labels will be recreated in Proton Mail.

Step 2

Migrate with zero downtime: Migration happens in the background, allowing your team to continue working while everything is transferred to your new secure inbox.

Step 3

Keep your custom domain: Proton Easy Switch lets you transfer messages directly to your custom email domain. Just configure it in Proton Mail first.

Step 4

Choose what to migrate: Migrate everything or just some of it. Easy Switch lets you choose how much to transfer over.

Switch to Proton Mail for Business Learn more