Table of contents:
Issue
When users try to report an email as phishing, a pop-up will appear, but the report button is not clickable.
Potential Cause
Monitor reported messages in Outlook isn't selected: The Microsoft-integrated reporting experience for email messages is turned off, and all settings related to reporting email messages aren't configurable on the User reported settings page, including the ability for users to report email messages from quarantine. [Reference]
Step-by-Step Solution
Sign in to https://security.microsoft.com/.
Alternatively, use the direct link:
Go to Settings > Email & collaboration > User reported settings.
βOn the User reported settings page, select the Monitor reported messages in Outlook settings from the top of the page.
Monitor reported messages in Outlook is selected. The following configurations are supported:
To report email messages, use the built-in Report button in Outlook on the web or the Microsoft Report Message or Report Phishing add-ins in virtually all Outlook platforms.
These steps should ensure that the reporting feature is enabled and properly configured in Outlook, allowing users to report phishing messages without the option being greyed out.