The first governance action for implementing a BYOD program should be to assess the BYOD risk. This is because BYOD introduces various security, legal, and operational risks to the enterprise, such as data loss or leakage, unauthorized access, malware infection, compliance violation, device management, and user privacy.
Assessing the BYOD risk can help to identify and evaluate the potential threats, vulnerabilities, and impacts of allowing employees to use personal devices for email. Assessing the BYOD risk can also help to determine the appropriate controls and mitigation strategies to reduce the risk to an acceptable level.
Assessing the enterprise architecture (EA) is not the first governance action, as it is a subsequent step after assessing the BYOD risk. EA is a framework that defines the structure, components, relationships, and principles of the enterprise's IT environment. Assessing the EA can help to ensure that the BYOD program aligns with the enterprise's vision, strategy, goals, and standards. However, assessing the EA does not address the specific risks associated with BYOD.
Updating the network infrastructure is not the first governance action, as it is an implementation step after assessing the BYOD risk and EA. Updating the network infrastructure can help to enhance the performance, reliability, scalability, and security of the network that supports the BYOD program. However, updating the network infrastructure does not provide a comprehensive risk assessment or governance framework for BYOD.
Updating the BYOD policy is not the first governance action, as it is a result of assessing the BYOD risk and EA. A BYOD policy is a document that defines the rules, guidelines, and responsibilities for employees who use personal devices for email. Updating the BYOD policy can help to communicate the expectations and requirements for BYOD users and enforce compliance and accountability. However, updating the BYOD policy does not provide a thorough risk analysis or architectural alignment for BYOD.
References := BYOD Best Practices - JumpCloud, Assessing your needs section. End user device security for Bring-Your-Own-Device (BYOD) deployment models - ITSM.70.003 - Canadian Centre for Cyber Security,
1 Introduction section. BYOD Policy Best Practices: The Ultimate Checklist - Scalefusion, Introduction section. The Ultimate Guide to BYOD Security: Definition & More - Digital Guardian, The Challenges of BYOD Security section.

Requiring the business to help define IT goals is the best way to establish alignment between business and IT when the IT department has been operating independently of business concerns. This collaborative approach ensures that IT initiatives are directly linked to business objectives, facilitating strategic alignment and ensuring that IT supports and enhances business operations. While IT defining business objectives, business funding IT services, and both defining risks are important, the foundational step for alignment is integrating business perspectives into the definition of IT goals.