Healthcare providers use email for referrals, appointment coordination, authorizations, and to communicate with caregivers and to conduct administrative tasks. Email filtering is a resource that protects providers and their processes from phishing, malware, impersonation, and spam.

These filters can sometimes quarantine or block legitimate emails, and factors like positives create delays, inevitably adding to the workload of healthcare IT departments. The 2026 Healthcare Email Security Report looked at 170 healthcare data breaches linked to email occurring in 2025. The report found that 74% of impacted domains had ineffective DMARC protection.

Statistics like these do not measure false positives, instead showing why healthcare organizations cannot reduce filtering errors by simply weakening security. Providers need controls that accurately distinguish legitimate healthcare communication from increasingly convincing attacks.

 

What is a false positive in email security?

A false positive refers to an email that is not spam, phishing, malware, or another type of threat, but is flagged by an organization’s email security systems as something that it is. The problem comes into play when the false positives are moved to a spam folder, quarantined, blocked, or deleted.

False negatives are the opposite of false positives. They occur when a malicious email bypasses an organization’s security measures and lands in a user’s inbox.

Legitimate business emails such as referral letters, lab alerts, insurance pre-authorizations, invoices, and patient communications often mimic malware emails. They can include suspicious links, password-protected attachments, urgent requests, newly registered domains and medical terms that would be unfamiliar to a broad spectrum filter.

Microsoft guidance recommends administrators begin troubleshooting false positives by identifying whether an email was flagged as spam or as a phishing or malware threat. Each category requires a different approach.

 

How do false positives disrupt patient care?

An email should never prevent important information from helping providers schedule appointments, follow up on referrals, secure prior authorization, or coordinate care. Just because a filter stopped a message does not mean it vanishes from the care workflow. Someone needs to recognize the delay, find the message, verify it is safe, and deliver it back to the right person.

Studies about inbox overload help explain why missed messages and false positives are noteworthy. According to a study on recommended practices for clinicians' inboxes, “Overall message volume led to inefficient processing associated with information overload and contributed to decreased SA level 1 as a result of an inability to differentiate between urgent and non-urgent messages.” The study was targeted toward EHR inboxes, not email security gateways, but the concept is still the same. Employees have to dig through dozens of warnings or quarantines just to find valid messages related to patient care.

Even research into drug alert notifications can serve as a cautionary tale for repetitive low-value warnings. From an article on alarm fatigue in hospitals, “Drug alerts, however, are not always beneficial, and patient harm can occur when low value or false positive alerts appear.” Drug alerts are not the same thing as email alerts. But both examples show how repeatedly alerting staff to low-risk threats can be counterproductive.

Healthcare providers can maintain secure email workflows that surface suspicious emails based on risk level. High-risk emails can be routed to admins for review, while known phishing and malware can be held back from clinical users.

 

Why was a legitimate healthcare email blocked?

Even a well-intentioned email can get flagged if its technical or behavioral patterns look like a known threat. For example, a brand new laboratory domain, an unanticipated attachment, a shortened URL, unexpected sending volume, or authentication failure may trigger a filter to label the message as malicious.

False positives can also be the result of a security update. Earlier this year, Paubox reported that a Microsoft Exchange Online URL filtering rule was incorrectly flagging legitimate messages as phishing. Microsoft confirmed the recent rule was the culprit and began efforts to release affected messages and whitelist legitimate URLs.

However, healthcare IT teams can look at several message components, such as the header, the filtering verdict, the sender's address, authentication outcomes, any URLs and attachments, relevant mail flow rules, and the block list entries that were engaged.

Microsoft explains that just by examining the message header, it is possible to see if the message was impacted by a spam verdict, bulk email threshold, blocked sender entry, connection filter, or custom organization policy. The most productive approach is to resolve the filter's trigger directly, rather than trying to get around it.

 

How can providers reduce false positives without weakening phishing protection?

Providers can start tracking recurrent false positives. When false positives repeatedly show up from the same sender, with similar message types, attachments, or filtering rules, it points to settings that are either too strict or do not account for healthcare-specific nuances. Administrators should be able to open the impacted message to see which security control returned the verdict. True newsletters misidentified as bulk spam should not be processed like a referral attachment flagged as malware.

Professionals can report verified false positives to their email security vendor, implement a narrowly scoped policy tweak, and forward themselves an email containing similar content to ensure the problem is fixed. Trace headers and message tracing will be able to verify if the adjustment addressed the problem. Adjustments should also be tracked moving forward. The goal for these organizations isn't to swap out a high rate of false positives for less effective phishing prevention.

When surveyed for the Paubox Healthcare Email Security Maturity Index 2026, 64% of healthcare entities confirmed they had been targeted by an email attack involving AI. However, only 38% of respondents said they had AI-based email threat detection solutions that were fully deployed and being actively monitored.

 

How do authentication and user feedback improve filter accuracy?

Email authentication allows receiving systems to verify that a message was sent through authorized infrastructure. SPF records are designed to declare the specific servers permitted to send emails for a domain. DKIM ensures email authenticity by adding a cryptographic signature, letting recipients verify the message's contents remain unchanged. DMARC ties those results to the domain shown to the user and instructs receiving servers how to handle messages that fail authentication.

Proper authentication can allow filters more confidence that a message is legitimate. However, authentication itself does not guarantee a message is harmless, since even legitimate accounts or services can be taken over. User and administrator input provide organizational context. Users can report a message as ‘not spam’. Administrators can provide details on confirmed false positives, log decisions about message releases, and flag recurring issues with known healthcare partners.

 

Which is safest between an allow list, spam folder, or quarantine?

It is acceptable to use a spam folder for messages containing low-risk spam or gray mail, such as unwanted newsletters and typical promotional emails. Users can retrieve legitimate messages they are expecting instead of requiring administrators to release every message rated as low risk.

Quarantine is more secure for suspicious messages that might contain phishing attempts, malware, suspicious attachments, attempts to impersonate another person or company, or sensitive information such as protected health information that caused a data loss prevention rule to trigger. Quarantine isolates the message until an authorized user or administrator reviews it and decides whether to release it.

An allow list creates an exception for a particular sender, domain, or mail system. Users can use an allow list to remedy a known delivery issue, but be careful when adding a large number of filters to it. Allowing entire domains can prevent messages from going through the entire filtering stack.

See also: HIPAA Compliant Email: The Definitive Guide (2026 Update)

 

FAQs

Why do password-protected healthcare attachments often trigger security filters?

Password protection can prevent an email security system from examining the contents of an attachment for malware. Healthcare organizations can establish an approved method for exchanging protected files and separately confirm unexpected passwords or attachments with the sender.

 

Should a healthcare organization lower its filtering threshold when too many legitimate messages are blocked?

A broad threshold reduction may allow more phishing, impersonation, and malware to reach employees.

 

How should healthcare organizations handle false positives involving urgent patient care messages?

Organizations can establish a priority review process for expected referrals, laboratory communications, prescription requests, and other time-sensitive messages. Staff should have a clear escalation route for locating and reviewing missing messages without automatically bypassing security checks.

 

Does placing a sender on an allow list make every message from that sender safe?

No, the sender’s account, domain, or authorized email service could later be compromised and used to distribute malicious content.