Leslie Nielsen joins Mimecast as Chief Information Security Officer

Leslie Nielsen, a seasoned cybersecurity expert, joins Mimecast as CISO to advance its global cybersecurity strategy.

  • Friday, 29th August 2025 Posted 8 months ago in by Aaron Sandhu

Mimecast, a global leader in cybersecurity, is welcoming Leslie Nielsen as its new Chief Information Security Officer (CISO). With over 25 years of experience in the cybersecurity field, Nielsen joins Mimecast from Klaviyo, a prominent marketing automation platform. In his previous role, he played a pivotal part in scaling Klaviyo to $1.3 billion in revenue, enhancing its security infrastructure, and preparing the company for the rigours of public market entry.

As Mimecast's CISO, Nielsen is tasked with spearheading the company’s global cybersecurity strategy. This involves overseeing significant areas such as threat intelligence, risk assessment, incident response, and ensuring regulatory compliance. These efforts are critical as Mimecast continues its mission to secure over 42,000 global customers.

According to Mimecast CEO, Marc van Zadelhoff, “We sought out a leader who can see beyond the noise and hype to deliver an innovative security platform, and Leslie fit the bill perfectly."

Nielsen is enthusiastic about his new role, saying “I’m thrilled to join Mimecast on their mission to secure the human layer in the new age of AI-powered security threats. The industry is at a pivotal point where defence strategies must place humans at the centre, and Mimecast has long been at the forefront of human side of security. I look forward to building on the company’s strong foundation and helping shape its next chapter of innovation and resilience.” 

Before his tenure at Klaviyo, Nielsen held senior positions with several major companies, including Nuance Communications, SAP Concur, SuccessFactors, and SOS Security. He has also been part of Google's CISO Cloud Advisory Board, showcasing his industry recognition and breadth of expertise. Nielsen's academic foundation is in computer science from Texas Tech University.

Nebula Global Services has achieved Cyber Essentials Plus certification, confirming independently assessed cyber security controls across its...
Mhance has appointed Andy Cowdrill to its leadership team, as the company continues to develop its Microsoft-focused strategy.

Westcon-Comstor strengthens ties at RISK Conference 2026

Posted 6 days ago by Sophie Milburn
Westcon-Comstor outlines its role in RISK Conference 2026, emphasising regional collaboration and cybersecurity advancements in the Balkans.

Talion’s cybersecurity model emphasising SME resilience

Posted 6 days ago by Sophie Milburn
A look at cybersecurity frameworks developed to better align security practices with operational risks.
Ci Distribution and 42Gears have partnered to provide resellers with device management and security solutions for use across multiple market sectors.

Node4 appoints new CEO and Non-Executive Chair

Posted 1 week ago by Sophie Milburn
Node4 has appointed Neil Muller as Chief Executive Officer and Patrick De Smedt as Non-Executive Chair, marking a leadership change as the company...
Arctic Wolf introduces Decipio, a cybersecurity tool, aiming to catch credential-stealing attempts early to protect networks better.
Exabeam has updated its Agent Behaviour Analytics to improve visibility into AI activity and strengthen enterprise threat detection capabilities.