Proofpoint buying Hornetsecurity in a play to expand email security scope

More than of 90% of successful cyberattacks begin with emails, according to the US Cybersecurity and Infrastructure Security Agency (CISA), making them a critical asset that enterprises must protect.

Cybersecurity vendor Proofpoint is looking to expand its reach in this area, announcing its intent to purchase Hornetsecurity Group, a European email security rival. The move will extend Proofpoint’s base beyond some of the world’s largest companies to small and mid-sized businesses (SMBs) globally, through managed service providers (MSPs).

“It’s an interesting move to diversify from Proofpoint’s bread and butter, large enterprise businesses, towards the small and medium-size business space,” noted David Shipley of Beauceron Security, a Proofpoint competitor.

What Hornetsecurity brings to Proofpoint

Hornetsecurity specializes in Microsoft 365 security; its flagship product is 365 Total Protection, which offers comprehensive email security, backup, access and permission control, and domain fraud protection.

Proofpoint says the move brings a “high-performing” business into its portfolio: Hornetsecurity, which launched in 2007, has more than 20% year-over-year growth and more than $160 million in annual recurring revenue (ARR). It has 12,000-plus channel partners and MSPs, and serves 125,000-plus SMBs across Europe.

Gartner’s Magic Quadrant for Email Security Platforms identified Hornetsecurity as a “niche player” in the market, while Proofpoint is a market leader.

“Hornetsecurity brings the ripe market of SMBs to Proofpoint for immediate upsell of Proofpoint to those customers, along with the established MSP relationships already enabled,” said Jimmie Lee, founder and CEO at JLEE.com.

Shipley noted that the purchase is “likely a direct response” to KnowBe4’s acquisition of Egress, another e-mail filter company that, he said, “makes Knowbe4 a direct competitor for Proofpoint’s most valuable products.”

In addition, “Hornetsecurity’s channel partners and its current revenue are both likely equally attractive parts of this deal,” he said.

One of many big purchases in the industry

While the terms are confidential, sources have reported the price of the Hornetsecurity purchase, which is expected to close in the second half of 2025, to be well over $1 billion. This would make it Proofpoint’s largest acquisition, and also one of the biggest cybersecurity deals in recent years.

Proofpoint is also reaping the benefits of Hornetsecurity’s own acquisition strategy. In March 2024, it acquired Vade, an AI-based email security platform that analyzes more than 2.5 billion messages daily. This helped Hornetsecurity bolster its detection capabilities for business email compromise (BEC) and spear phishing. The company has also enhanced its platform through several other acquisitions, including Altospam (anti-phishing software), IT-Seal (cybersecurity training), Zerospam (email security and anti-spam), and Everycloud (email security).

Proofpoint has also been exploring other acquisitions and different funding routes as it reportedly prepares to return to public markets in 2026. Earlier this year, it also expanded its global partnership with Microsoft, using Microsoft Azure’s AI capabilities and cloud infrastructure to enhance threat protection and data security.

With this strategy, it is reflecting trends in the security market. In March, Google stunned the industry when it announced it was buying cloud security company Wiz for $32 billion, its biggest acquisition of any kind to date. Meanwhile, Palo Alto Networks is purchasing AI and ML security company Protect AI in a deal valued at roughly $700 million; Cisco paid $28 billion last March for cloud security platform Splunk (also its biggest ever, and following a slew of other acquisitions); and Thoma Bravo bought Darktrace for $5.3 billion in April. Not to mention, Proofpoint itself was purchased by Thoma Bravo for $12.3 billion in 2021.

“All of these acquisitions signal two main themes: Innovation by acquisition and growth velocity through strategic market penetration,” said Lee.

Large companies need to move quickly in increasingly competitive markets, and without acquisitions, it can take years to expand into new areas, he noted, and potentially requires internal reorganizations, tough recruiting cycles, and untold expenses. Acquisitions bring in customers and MSPs, as well as talent with a “proven working culture.”

Ultimately, this represents a “growth point” for cybersecurity, said Lee, where the traditional approaches of software and SaaS-based companies are making their way into the industry.