Email Security Responsibilities

I'm curious how other organizations are handling roles & responsibilities from an email security perspective. What I'm trying to figure out is what should be handled by SysAdmin/Server Team and what should be handled by Security Team.

Specifically I was thinking through:
User Reported Phishing

Platform to Automate User Reported Phishing (We are using Proofpoint TRAP/CLEAR)

Releasing emails from quarantine

Domain/Sender Whitelisting, etc

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