A Mimecast developer constructs, tests, and maintains applications and systems to secure and streamline Mimecast's email security services. They work on a cloud-based platform, developing software to protect against phishing, spam, and malware attacks. They use coding languages like Java, C#, or Python and work with databases. They also solve technical issues, improve system performance, and integrate the software with other systems. Additionally, they may collaborate with other teams to understand user needs, contribute to system design, and ensure the software meets quality standards. They must stay updated about new technologies and cybersecurity threats.