Top Email Security Controls for Preventing Business Email Compromise in 2026

Business Email Compromise (BEC) is still one of the fastest ways for criminals to get paid because it targets how work actually happens: invoices, payroll, vendor changes, and executive requests. In Sacramento and nearby communities, that often means a small accounting team, busy clinic front desks, and vendors who communicate mostly by email. The result is a risk profile that is less about malware and more about trust.

A modern BEC defense plan for 2026 needs to assume two things at the same time: attackers can spoof domains convincingly, and they can also take over real mailboxes and reply inside existing threads. That is why the best programs stack controls across domain protection, identity security, detection, and business process.

Why BEC still works in 2026

BEC is rarely “click this bad link and run this file.” Many BEC messages contain no attachment, no obvious phishing URL, and no typos. They read like normal business.

Common patterns include:

• Fake invoice “correction”
• Bank details “updated”
• Payroll direct deposit change
• Gift card request
• Vendor email thread hijack
• “Sent from my phone” urgency cue

AI-written text has made the writing cleaner, faster to produce, and easier to tailor to your org chart and vocabulary. That pushes defenders toward controls that validate identity, catch anomalies, and slow down risky payments.

Control 1: SPF, DKIM, and DMARC with real enforcement

If your domain can be spoofed, attackers can send “from the CEO” or “from AP” messages that pass casual inspection. SPF, DKIM, and DMARC are the core controls that reduce that risk.

• SPF: tells the world which systems are allowed to send mail for your domain.
• DKIM: cryptographically signs outbound mail so recipients can verify it was not altered and came from an authorized sender.
• DMARC: sets the policy for what to do when SPF or DKIM fails, and it provides reporting so you can see who is sending on your behalf.

The biggest mistake is stopping at DMARC monitoring (p=none) and never moving to enforcement. Monitoring is useful, but it does not block spoofing. A practical rollout is: inventory your legitimate senders, fix SPF/DKIM alignment, move to quarantine, then to reject.

A single sentence that matters: DMARC only protects you when you tell receivers to reject unauthorized mail.

Sacramento reality check: third-party senders

Healthcare organizations, manufacturers, and professional services firms often have multiple mail streams: EMR reminders, ticketing systems, marketing platforms, cloud fax services, and line-of-business apps. DMARC projects fail when those sources are not identified up front. A managed DMARC reporting tool can help by turning XML reports into a list of real senders to approve or shut down.

Control 2: Modern anti-phishing that focuses on BEC, not just malware

Legacy secure email gateways were built to block spam and malware at the perimeter. BEC is different. The message might come from a newly registered domain that looks similar to yours, or from a real vendor mailbox that was compromised.

In 2026, strong email protection tends to include:

• API-level detection integrated into Microsoft 365 or Google Workspace
• Behavioral and relationship analysis (who normally emails whom, and how)
• Impersonation detection for executives, finance, and vendors
• URL rewriting and click-time inspection
• Attachment detonation where it fits your workflow

This is also where local operations benefit from a Security Operations Center (SOC) workflow. If your alerting goes nowhere after hours, attackers get time to set mailbox rules, exfiltrate messages, and time a payment request for Monday morning.

Control 3: Phishing-resistant MFA plus conditional access

SPF, DKIM, and DMARC do not help when the attacker logs in as a real user. Many BEC incidents start with stolen credentials, token theft, or malicious OAuth app consent.

MFA is the baseline, but not all MFA is equal. SMS and push approvals can be abused through social engineering and real-time phishing proxies. A stronger target state is phishing-resistant MFA (FIDO2 security keys or certificate-based methods), paired with conditional access.

Conditional access can block risky sign-ins by requiring:

• A managed device
• A compliant device posture (disk encryption, screen lock, OS patch level)
• A trusted location or VPN condition where appropriate
• A step-up challenge for high-risk actions

This matters for clinics and regulated businesses because the mailbox is often the gateway to patient data, billing details, and portal password resets.

Control 4: Reduce “silent takeovers” by hardening mailbox behavior

BEC actors love persistence. They create inbox rules to hide replies, forward mail externally, or move security alerts to RSS folders. They also add unauthorized delegates or create new OAuth grants that survive password changes.

Good controls here are not flashy, but they are effective:

• Mailbox auditing and alerting for rule creation, forwarding changes, and delegate access
• Blocking auto-forwarding to external domains unless explicitly approved
• Restricting who can create transport rules and connectors
• Reviewing OAuth app consents and restricting third-party app access by policy

If your organization uses Microsoft 365 or Google Workspace, these settings exist, but they need to be turned on, tuned, and monitored.

Control 5: Encrypt transport, and sign sensitive roles

Encryption is not a complete BEC fix. If a mailbox is compromised, the attacker can send “encrypted fraud” too. Still, encryption and signatures close real gaps:

• MTA-STS and TLS-RPT: reduce downgrade attacks and enforce TLS for SMTP transport where supported.
• S/MIME signing for high-risk users: helps recipients verify that a message really came from your accounting or leadership team and was not altered.

For healthcare organizations and any team sending regulated data, encryption also supports compliance expectations around safeguarding sensitive information in transit.

Control 6: Put guardrails around money movement

The most effective BEC control is often not email-specific. It is a payment process that assumes email can be wrong.

After you document your normal payables and payroll paths, add friction where it counts:

• Verification for changes to bank routing details
• Dual approval thresholds for wires and ACH
• Vendor master file change control
• Known-good callback numbers that are not taken from the email being verified

This is where security and finance should agree on a “stop and verify” rule that is simple enough to follow on a busy day.

A practical control map for 2026

The table below is a helpful way to plan. It separates what each control blocks, where it is configured, and what tends to be overlooked.

What a minimum baseline looks like for many Sacramento SMBs

Not every organization needs the same stack on day one, but a baseline should still be measurable. A good starting point is:

• Domain protection: SPF and DKIM validated, DMARC reporting turned on
• DMARC enforcement: Move from monitoring to quarantine, then reject after tuning
• Account security: MFA for all users, phishing-resistant MFA for admins and finance
• Log visibility: Centralized alerting for mailbox rules, forwarding, and risky sign-ins
• Payment safety: Written verification steps for bank change requests

That baseline blocks a large portion of spoofing and slows down the “reply inside a real mailbox” attacks long enough for detection to work.

Healthcare and EMR workflows: a few extra considerations

Healthcare organizations often have more external messaging: patient notifications, referral coordination, billing communications, lab portals, and EMR integrations. Those create extra domains, extra senders, and more opportunities for attackers to impersonate “normal.”

Two practical steps help a lot:

Control your domains and subdomains. Use separate subdomains for bulk or third-party sending so DMARC policy can be strict on the primary business domain while still supporting legitimate mail streams.

Treat shared mailboxes as privileged assets. Scheduling, referrals, and billing shared inboxes can carry patient and payment context. Apply MFA, conditional access, auditing, and tighter delegation rules.

Business PC Support often helps Sacramento-area organizations plan these controls with compliance and operations in mind, including secure integrations around EMR-related messaging where it intersects with identity, logging, and change control.

What to prioritize in the next 30 to 60 days

Start with changes that reduce the most risk without breaking daily operations.

A solid short plan is:

1. Get DMARC reporting running, then work toward enforcement after you validate all mail streams.
2. Tighten identity: phishing-resistant MFA for admins and finance, conditional access for everyone.
3. Turn on mailbox and OAuth monitoring, and make sure alerts reach someone who can act.

BEC prevention is less about buying one product and more about making it hard to spoof you, hard to take over accounts, and hard to move money without verification. In 2026, that layered approach is what consistently reduces losses.