In recent months, cybersecurity analysts have observed a sharp increase in the number and scale of data breaches, affecting businesses across every sector. One such breach exposed billions of usernames and passwords across major digital platforms. While much of the data appears to be aggregated from older leaks, the sheer volume and the public attention it generates, has had a significant ripple effect, particularly in the form of email-based attacks.
The Danger of Follow-On Attacks
Large-scale credential exposures often function as the opening act to a much broader playbook. Cybercriminals don’t need freshly stolen credentials to wreak havoc. What they rely on is human error, password reuse, and the natural panic that follows media reports of large data breaches. As soon as such an incident makes the news, attackers mobilise quickly. Phishing campaigns, credential harvesting attacks, and fake password reset requests are often launched within hours.
These scams are not random. They are designed to exploit heightened awareness. Victims who are concerned about their online security are more likely to open a warning email or respond to an alert. This is why post-breach phishing is often more successful than standard campaigns. The attacker doesn’t just rely on deception, they leverage public fear and urgency.
In 2025, the scale of these follow-on campaigns is growing, and email is their primary weapon. Fake security alerts, impersonated support requests, and cloned login pages are all part of a cybercriminal’s response playbook to a data breach. Businesses may not even be the original target, but once a credential is compromised and repurposed, it becomes the attacker’s foothold into your client's corporate infrastructure.
Email: An Amplified Threat
The risks are magnified for businesses that rely on email to drive key processes. Think of how many workflows hinge on a single inbox: invoices, approvals, client communications, and login links. One exposed credential tied to a business email address can provide attackers with a gateway into systems that were never intended to be externally accessed.
The problem is further amplified by the growing number of third-party apps and integrations linked to email accounts. Once attackers gain access to an inbox, they can exploit tokens and cookies to impersonate users across connected platforms. In many cases, they don’t need to reset passwords at all, they simply ride the existing session until they’re finished extracting value.
One of the growing tactics following these breaches is credential stuffing, where attackers use bots to test thousands of username and password combinations across various services. If users have reused passwords across personal and professional accounts, the likelihood of a breach cascading into the workplace increases significantly.
A Critical Role for Partners
Managed Service Providers and cybersecurity consultants must be proactive in this environment. These breaches, and their inevitable email fallout, provide a clear window to educate clients about the importance of layered security. Businesses may feel removed from the breach itself, but their exposure is real, and it arrives quietly, in the form of a well-timed phishing email.
Post-breach phishing campaigns frequently use branding and language from well-known platforms. Emails may reference recent news reports, claiming to be from trusted entities and urging users to change their passwords or verify their identities. These emails often link to cloned sites designed to steal updated credentials, which are then sold or used for further compromise.
The deception doesn’t end with login details. In some cases, attackers request multi-factor authentication (MFA) codes during the login process, capturing full access in one strike. This technique, often referred to as MFA fatigue or prompt bombing, involves repeatedly sending MFA requests to users until they accept one out of frustration or distraction.
This wave of post-breach fraud is also being used to gain access to financial platforms and HR systems. For instance, compromised business emails are used to request payroll changes, redirect payments, or alter supplier banking details. These social engineering tactics blend with technical compromise to create a perfect storm of vulnerability.
What’s clear is that in today’s environment, data breaches don’t just end with stolen information. They mark the beginning of an extended campaign, where email becomes both the delivery mechanism and the target. Every business must treat public data breaches as a trigger for internal scrutiny. Are employees using strong, unique passwords? Are they aware of how to verify legitimate password reset requests? Are email accounts monitored and protected beyond the native platform controls?
As email remains the most common and easily exploited point of entry into businesses, security must evolve. Traditional protections are not sufficient to stop modern threat actors who move quickly and mimic the digital identities of trusted platforms and colleagues.
For partners and MSPs, this is a crucial time to drive meaningful conversations about email security with clients. These events highlight just how interconnected today’s threat environment has become, and how rapidly a breach elsewhere can become a problem at home.
Keeping Businesses Safe and Secure
Prevention is always better than a cure, and one of the best defences is to encourage businesses to proactively boost their company’s cyber resilience levels to avoid threats landing in inboxes in the first place. The fact that a staggering 94% of malware attacks are delivered by email, makes email an extremely important vector for businesses to fortify.
No one vendor can stop all email threats, so it’s crucial to remind customers that if they are using Microsoft 365 or Google Workspace, they should also have a third-party email security specialist in place to mitigate their risk. For example, using a specialist AI-powered email threat detection solution like MailGuard.
For a few dollars per staff member per month, businesses are protected by MailGuard's specialist, zero zero-day email security. Special Ops for when speed matters! Our real-time zero zero-day, email threat detection amplifies your client’s intelligence, knowledge, security and defence.
MailGuard provides a range of solutions to keep businesses safe, from email filtering to email continuity and archiving solutions. Speak to your clients today to ensure they’re prepared and get in touch with our team to discuss fortifying your client’s cyber resilience.
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