Senior Product Designer in London

Design the experience that stands between businesses and their biggest threats.

At Mimecast, design is not decoration - it is the difference between a threat that gets caught and one that doesn't. As our Senior Product Designer for Email Threat Protection, you will shape the experiences that help security teams, IT administrators and everyday users stay ahead of increasingly sophisticated attacks. This is a role for a designer who builds. You will work at the intersection of craft, technology and genuine human need - using AI-native tools alongside deep design thinking to move from rough concept to production-quality UI with speed and conviction. Your work will be seen and used by millions of people across the globe, every single day.

What our team says

“Designing at Mimecast means your work genuinely matters. The problems are hard, the team is brilliant, and you can see the direct impact of what you build on people who are trying to protect their organisations every day. There is no shortage of meaningful things to work on here and you truly can make a design impact.” — Zarina Osman, Senior Product Designer, Email Threat Protection

A note from the hiring manager

“I’ve spent a long time in product, and I can count on one hand the roles where a designer genuinely gets to define the direction - not just execute it. This is one of them. We’re at a point where the product is evolving faster than the experience has kept up, and we’re fixing that deliberately. The designer who joins us will be working on something that protects real people from real threats every single day. That’s not abstract. Getting that experience right, making it clear, human, and intelligent, is one of the most important things my team will do in the next two years.” — Marc Amphlett, Senior Director, Email Threat Protection — Product Management

What You’ll Do:

• Lead design end-to-end
• Drive the full design process for Email Threat Protection features - from discovery and problem framing through to polished, production-ready UI.
• Work at the right fidelity for the moment: sketches and flows when speed matters, pixel-perfect detail when quality does. Both matter here.
• Apply strong UI fundamentals - typography, layout, colour, hierarchy - to make complex, AI-driven security data feel clear and human.
• Own and evolve the design system
• Go deep on our design system - understand its architecture, token structure and principles before proposing change.
• Author documentation for components, patterns and templates: usage guidance, accessibility notes, do/don’t examples and the intent behind decisions.
• Contribute net-new patterns and enhancements - defining behaviour scope, states and variations that extend coverage without fragmenting consistency.
• Build with AI
• Use Cursor, Claude, Figma Make and equivalent agentic coding tools to move from design to working prototype to production-quality frontend - compressing the handoff into a fast, single loop.
• Prototype interactions for AI-assisted threat detection, automated triage and copilot-style admin interfaces at a pace that would have been impossible two years ago.
• Continuously adopt new AI tools and share what you learn - we grow faster as a team when we learn out loud.
• Design intelligently for AI behaviour
• Create UX patterns that surface AI confidence, uncertainty and reasoning in ways that inform rather than overwhelm.
• Partner with AI/ML engineers to ensure what the product shows accurately reflects how the models actually behave.
• Define interaction patterns for automated triage, anomaly explanations and policy recommendations - balancing automation with transparency and user control.
• Discover, collaborate, influence
• Validate direction continuously with user research, analytics and qualitative insight - bring evidence, not just intuition.
• Advocate loudly for our users: security administrators, IT teams and the people on the frontline of email threats.
• Build strong relationships with Product and Engineering through stand-ups, workshops and open collaboration. Unblock dependencies without losing sight of the experience.
• Champion Design Thinking across the business and set clear expectations with stakeholders at every level.

What You’ll Bring:

Essential

• In-depth product design experience with a portfolio of shipped B2B or SaaS work - products, not concepts.
• Mastery of Figma and a toolkit that spans lo-fi exploration through to pixel-perfect delivery.
• Active, demonstrable use of AI-native prototyping workflows - you already use agentic tools to produce working UI, not just describe how you would.
• Strong UI foundations: typography, layout, colour theory and visual hierarchy - you know what makes an interface feel trustworthy.
• Meaningful experience contributing to a design system - documenting components, defining behaviour, maintaining patterns and treating it as a living resource.
• Sharp analytical and communication skills. You can make the case for a design decision as confidently as you can make the design itself.
• Experience in Agile, multi-disciplinary squads and a track record of designing against real user needs, not just requirements.

Great to have:

• Experience designing for AI, LLM-powered or conversational products, with an understanding of how non-deterministic behaviour shapes UX.
• Background in security, data-heavy or enterprise admin interfaces.
• A portfolio that shows before/after impact: designs that measurably improved engagement, comprehension or task success.
• Familiarity with WCAG 2.1 AA accessibility standards.
• Experience with motion design or advanced prototyping tools (Framer, Rive or code-based animation).

What We Bring:

Mimecast is at an exciting point in its product journey. We have recently adopted a Product Accessibility Policy, are actively embedding AI into our platform, and are investing in the quality of our design practice in ways that will be visible to customers. This is a role where the work is genuinely consequential, the problems are hard, and the team cares about getting it right.

You can expect:

• A design-led environment where your voice carries weight in product decisions.
• A cross-functional squad that is collaborative, curious and low on ego.
• Real investment in your use of AI tooling and modern design workflows.
• A commitment to accessibility and inclusive design baked into how we build.
• Opportunities to contribute to a design system that shapes the whole platform, not just your squad.

AI-First Engineering at Mimecast

Mimecast is an AI-First engineering organization. Our teams actively leverage AI-powered development tools across all facets of engineering, from code development to testing, documentation, and operations. We're looking for leaders who don't just use AI tools but champion their adoption and establish new ways of working.

Our AI leadership extends beyond how we build to what we build. Our Mihra AI agent delivers 7x faster threat response for customers, and we're recognized as "Agents of Change" in Human Risk Management. Engineers here work at the intersection of cutting-edge AI tooling and AI-powered security products that protect organizations worldwide.

Career Growth Opportunities

This is a senior individual contributor role within a flat, collaborative design structure. What this role offers instead is genuine ownership: the space to define how great UX is done at Mimecast, to shape AI-powered experiences that are new territory for our field, and to build a body of work that is meaningfully complex and consequential.

You will have the opportunity to become a recognised voice on AI UX within the Design & Research practice, to deepen expertise in security-specific design challenges that are genuinely novel in our field, and to grow your influence across the wider product organisation as a champion of user-centred thinking. For the right person, that kind of craft-led growth - with real autonomy and real impact - is the opportunity.

The Team & How We Work

The Email Threat Protection squad sits within Mimecast’s Design & Research practice. We work in an open, collaborative way - designs are shared early, feedback is direct, and there is a strong culture of learning from each other. We use Figma as our primary design environment and maintain close working relationships with product and engineering through regular ceremonies and informal 1-2-1s.

We believe that great design in cybersecurity is not just about usability - it is about trust. Every interaction we design is an opportunity to help someone feel more in control, more informed, and more confident in the face of a threat. That is the standard we hold ourselves to.

Ready to protect millions — one interaction at a time?

The base salary range for this position is £68,000−£102,000 plus benefits. This range represents the minimum and maximum new hire compensation for this role. The position may also be eligible for incentive plans and additional benefits, in accordance with company policy and local regulations. Our salary ranges are determined by role, level, and location with individual compensation also dependent on factors such as qualifications, experience, and skills. Final offers will reflect these considerations and may vary accordingly.

Belonging at Mimecast

Cybersecurity is a community effort. That’s why we’re committed to building an inclusive, diverse community that celebrates and welcomes everyone – unless they’re a cybercriminal, of course. We’re proud to be an Equal Opportunity and Affirmative Action Employer, and we’d encourage you to join us whatever your background. We particularly welcome applicants from traditionally underrepresented groups.

We consider everyone equally: your race, age, religion, sexual orientation, gender identity, ability, marital status, nationality, or any other protected characteristic won’t affect your application.

Due to certain obligations to our customers, an offer of employment will be subject to your successful completion of applicable background checks, conducted in accordance with local law. It is unlawful in Massachusetts to require or administer a lie detector test as a condition of employment or continued employment.