Data exfiltration is a massive cybersecurity risk because it involves sensitive information quietly leaving the network without anyone’s permission. Managed security service providers (MSSPs) step in to reduce that risk by watching email activity around the clock and using smarter tools to spot problems early.
Their focus on email is well-placed, especially when considering that as noted in a PLoS One study, “In the digital era, email persists as a mission-critical communication channel, retaining its role as an efficient, cost-effective, and ubiquitous tool for both personal and organizational exchanges, despite competition from instant messaging platforms and social media.” The same study warns that “modern email systems enable seamless collaboration, yet their ubiquity comes at a cost,” because attackers increasingly hide malicious actions inside everyday messages.
To counter that, MSSPs use automated, AI-supported monitoring to scan outbound traffic for anything that doesn’t match a user’s normal behavior. These monitoring tools may discover strange recipient patterns, sudden spikes in how much data someone sends, or attachment types that look out of place. This is necessary because “studies indicate that up to 90% of cyberattacks originate from email-based threats,” and the volume of unwanted or malicious email grows daily.
The study further states, “Spam remains a long-standing issue, flooding internet users with vast volumes of unwanted content,” and many of these messages are simply a disguise for social engineering, credential theft, or exfiltration setups. Traditional security tools aren’t built for this landscape anymore, since “traditional spam detection methods typically rely on predefined rules,” and attackers have learned how to bypass those rules with constant variation. That’s why MSSPs rely on machine learning models that learn what normal email behavior looks like and then flag whatever deviates from it.
Email remains a prime channel for data exfiltration because it’s everywhere and used constantly. With more than 300 billion emails sent each day, malicious activity easily blends into normal traffic. Attackers hide stolen data inside ordinary-looking messages or impersonate executives and trusted contacts to trick users into handing over credentials or forwarding sensitive information. Social engineering thrives in this environment, which is why so many breaches start with phishing or spoofed internal emails.
Email systems were built for delivery, not security, and even with TLS in place, nothing stops a compromised account or insider from sending data out. Attackers take advantage of built-in features, auto-forwarding, delayed delivery, encrypted attachments, cloud-synced drafts, to quietly move information without triggering traditional content filters. Security tools often miss these behaviors because they focus on scanning messages, not the context or timing behind them.
Detecting exfiltration is even harder because email habits vary widely across roles. A spike in activity for one employee might be normal for another. Static rules and keyword lists can’t capture these nuances. Effective monitoring needs behavioral baselines, normal send times, typical recipients, usual file sizes, and AI models to spot anomalies such as new forwarding rules, unexpected external domains, or sudden large attachments.
Managed service providers (MSPs) struggle with spotting advanced email exfiltration because most still rely on rule-based or signature-based detection. Those tools can catch the obvious stuff, basic malware and clumsy phishing, but they miss the attacks that hide in plain sight. As one healthcare-focused BMJ Health & Care Informatics study states, “Hospitals receive a significant volume of potentially malicious emails. While many staff appear to be aware of phishing and respond appropriately, ongoing education is required across the spectrum of cybersecurity.” The research behind this finding shows the scale of the problem: “During the 1-month testing period, the organisation received 858,200 email messages… and 18,871 (2.2%) [were] identified as potential threats.”
Most MSPs don’t have the tools or staffing to continuously monitor user behavior or build dynamic email baselines. Subtle signs of exfiltration, new auto-forwarding rules, unfamiliar recipient domains, unusual sending times, or sudden spikes in attachment size, require machine learning and anomaly detection to catch. MSPs focus heavily on keeping systems running, which means they rarely deploy this level of analytics. As a result, insider threats and sophisticated external actors often slip right past their monitoring.
MSPs also tend to operate without full integration into threat intelligence platforms or CASBs. It’s even more dangerous now that so much exfiltration happens through cloud services, shared storage links, or indirect pathways attached to email. Without visibility into cloud activity or external threat indicators, MSPs are left with blind spots that attackers can easily exploit. When email, cloud tools, and external services aren’t monitored together, exfiltration attempts can move through gaps in the system without triggering any alarms.
MSSPs set themselves apart from traditional MSPs because they focus entirely on security, not general IT upkeep. Their work revolves around threat intelligence, vulnerability scanning, firewall and intrusion detection management, endpoint protection, and helping organizations stay compliant with HIPAA. They’re built for defense, not routine IT maintenance.
‘The mesa security model 2.0: A dynamic framework for mitigating stealth data exfiltration’ captures the shift perfectly, noting that “the rising sophistication of threats requires a shift from traditional security measures to more dynamic strategies that incorporate cutting-edge technologies and a thorough understanding of both the cyberthreat landscape and the specific tactics used by attackers.” That reality is exactly why MSSPs exist; they’re designed to handle threats that traditional IT teams simply aren’t built to manage.
Instead of reacting to problems after they happen, MSSPs take a preventive approach. They continuously hunt for threats, monitor systems for suspicious activity, and step in quickly when something looks wrong, often through managed detection and response services that alert teams and help contain an incident before it spreads.
When it comes to stopping data exfiltration through email, MSSPs use a layered strategy rather than relying on simple filters. Email is still one of the easiest ways attackers move data because everyone uses it and most companies depend on it for daily communication. To keep pace with that risk, MSSPs combine machine learning, behavioral analytics, deep content inspection, and real-time threat intelligence.
Their tools scan huge volumes of email traffic and look for anything that doesn’t fit a user’s normal patterns, sudden jumps in message volume, unusual external domains, odd attachment formats, encrypted or compressed files meant to hide sensitive information, or newly created forwarding rules that no one can explain. By putting all of these signals together, MSSPs can spot exfiltration attempts long before they become full-blown breaches.
See also: HIPAA Compliant Email: The Definitive Guide (2025 Update)
Phishing remains the top cause of data breaches because attackers rely on deception, not vulnerabilities. A convincing email or text message tricking a user into clicking a link or sharing credentials often becomes the attacker’s entry point.
Stolen usernames and passwords allow attackers to log in as real users.
Absolutely. Misconfigured cloud storage, open ports, weak access controls, and outdated firewall rules create gaps that attackers can easily exploit.