Leslie leads Mimecast’s global cybersecurity strategy as CISO, including threat intelligence, risk management, and detection and response, while ensuring regulatory compliance to protect Mimecast’s more than 42,000 global customers. With over 25 years of cybersecurity experience, he is known for driving innovative security strategies and building resilient, high-performing teams. He joined Mimecast from Klaviyo, where he served as SVP and CISO and helped scale the company to $1.3 billion in revenue, strengthen its security posture, and lead its security function through IPO. Before that, he was SVP and CISO at Nuance Communications, joining after a major malware attack to lead an accelerated security transformation that helped position the company as one of Microsoft’s largest acquisitions.
Earlier in his career, Leslie held senior security leadership roles at SAP Concur and SuccessFactors as VP and CISO, served as CTO at SOS Security, and held senior positions at IBM and ACS (acquired by Xerox); he has also served on Google’s CISO Cloud Advisory Board. Leslie holds a Bachelor of Science in Computer Science from Texas Tech University.
