Top 5 Email Security Threats
Email security threats aim to leverage the implicit trust between an email’s recipient and its sender. Today’s threats are drastically increasing in legitimacy, with AI-powered phishing now the most dominant threat to public-facing teams. The skill of modern phishing campaigns often exceeds the training and tools employees are issued. All team members are at heightened risk of supply chain compromise, as email threat trends far outpace traditional spam threats.
The Importance of Email Security
For the vast majority of businesses today, email is a key platform for conversations – especially with peers and colleagues outside their core team. Furthermore, employees often use their work emails to sign up or log in to large swathes of online accounts – making email addresses highly difficult to secure. All it takes is a data breach within one of those applications for an employee’s email to fall into the wrong hands.
In May 2025, US government-compliant messaging app TeleMessage suffered a data breach that exposed the email addresses of over 60 accounts. Former heads of US national security were impacted.
5 Most Common Email Security Threats for Enterprises
With the integrity of email addresses at greater risk than ever, it’s important to delineate the precise threats that face today’s email users.
#1. Phishing
The phishing email threat is now universal. Phishing campaigns attempt to abuse the trust that an email user places in pre-existing senders or brands. Usually, the contents of the email is the attack vector; it’s how the victim reading it is persuaded or tricked to act against their best interests.
Since human employees aren’t patchable, phishing plays a role in the majority of all cyberattacks. Many attackers opt for prebuilt phishing software packages sold on the dark web. These provide attackers with all the tools and elements needed to draft attack email messages, build associated web pages, and craft social media messages.
More advanced toolkits allow for the bulk import of victim email addresses, and a control center with a user interface. Attackers can use this control center to tailor how a phishing page captures stolen data, and where it’s sent. As a result, lower-skilled attackers are now able to launch convincing phishing campaigns using off-the-shelf services. This increases the volume and variety of attack messages seen in the wild.
In opposition to these bulk attacks, a spear phish is an email or message that targets a specific victim. The attacker may first collect as much personal information on the victim as possible from public-facing social media pages. The result is a finely-honed phishing attack that is less likely to be recognized as such. Whaling is the application of spear phishing against high-level executives, as ‘whales’ represent a far greater area of attack post-compromise.
#2. Supply chain compromise
Supply chain compromise allows attackers to take advantage of the implicit trust between a vendor and its partner organization. This is deeply valuable for attackers, as it allows them to send malicious emails from genuine, trusted accounts. In this way, Business Email Compromise (BEC) has one of the largest blast radii of any attack.
Supply chain email attacks bypass standard security filters, as the email originates from a previously vetted source. Exposed to the malicious email, the recipient is also far more likely to lower their guard and click embedded links, disclose credentials, and download malware-laden attachments.
#3. Domain Squatting
The less technical version of supply chain compromise, domain squatting sees an attacker attempt to pass as a legitimate counterpart in order to earn the recipient’s trust. All domain squatting attacks rely on registering domains that make small, imperceptible changes to genuine sites’ URLs.
Typosquatting deliberately includes minor typos within a section of their malicious URL. They may omit a letter, and change “checkpoint” to “checkpnt”; the goal is to pass an initial glance when the typo is nested within the wider URL. Combosquatting, on the other hand, sees a genuine domain name combined with an additional word – such as “checkpointsales”. This domain trickery could even include homograph attacks, which see similar-looking letters swapped for another “checkpoint” to “checkp0int”.
By registering a lookalike domain, attackers can craft their webpages to mimic the targeted brand’s login portals and support sites. Email spoofing then allows them to send the malicious URL out, under the facade of the genuine brand.
#4. Malicious Attachments
It’s not just the text of an email that could put a reader at risk. Malicious attachments are a frequent component of email security; they serve as a direct delivery method for malware onto victims’ devices. Cybercriminals often embed harmful files in emails, disguising them as legitimate documents to lure recipients into opening them.
For example, a ransomware email may include an attachment that asks the reader to enable content in order to view the document properly. Once enabled, the hidden code executes, granting attackers a foothold in the system. To further evade detection by security tools, these emails often contain little to no text in the body, drawing attention instead to the attachment itself.
#5. Multimodal AI Campaigns
Attackers are increasingly pushing at the boundaries of email security: AI phishing attacks are seeing a drastic increase in attack effectiveness. Part of this is their ability to leverage more than one communication channel at a time. For instance, an attack may include an email from a supposed company director, containing a link to a Teams meeting.
While on this Teams meeting, an attacker can then use GenAI to modify their voice to match the company director’s, using a model trained off the company’s previous conference or promotional material. Deepfakes can make this ruse even more convincing, as attackers can leverage both audio and visual deception.
Email Security Best Practices and Tools
Threats against email security originate from a mix of social engineering, technical malpractice, and now generative AI. To combat this, email protection can be broken down into three key areas.
Employee Training
Enabling employees to protect themselves allows for substantial strides in email security across the entire breadth of an organization. Furthermore, there are tools and platforms that help train employees. They can offer awareness training – in which employees are shown current attacks leveraged against their role, or industry – as well as phishing simulations. These tests allow an organization to keep an up-to-date profile of how protected its employees are from social engineering.
Technical Security Tools
In many cases, email attackers rely on their own infrastructure. Email security tools are able to check the domain owner, activity, and reputation of a linked URL, even before the email reaches a recipient’s inbox. The approach can range from more basic – like checking the URL against a pre-established list of phishing sites – to applying machine learning algorithms that identify patterns associated with phishing attempts.
AI
Finally, it’s possible to deploy AI against attackers. Email security tools that deploy Natural Language Processing can assess a message’s contents and intended tone, in order to establish a risk profile. Common phishing maneuvers – like urgency and outright threats – can be flagged for further inspection, giving the recipient a chance to spot the ruse. More advanced tooling can prevent BEC and insider email threats, as they identify deviations from a trusted sender’s style of speech and writing. It’s why AI is becoming an essential component of email security.
Gain Full Email Security with Check Point Harmony
Check Point Harmony is a fully-equipped security platform that identifies, trains, and secures against phishing and account takeover attacks. Rather than rely solely on email, Harmony first establishes what data is flowing into and out of an organization. It then issues security controls around each endpoint, with specific focus placed on day-to-day email exchanges. Rather than a basic email gateway, Check Point links email analysis with real-time endpoint data, allowing for a more in-depth risk profile of each machine. In the event of account takeover, unauthorized user access can be blocked immediately.
Suspicious emails are identified with cutting-edge AI, and quarantined for further analysis by the organization’s security team. These are then fed into Harmony’s phishing training AI, to support end-users in their training. Explore it for yourself with an email security demo.
