Search for and delete email messages in your Office 365 organization
You can use the Content Search feature in Office 365 to search for and delete an email message from all mailboxes in your organization. This can help you find and remove potentially harmful or high-risk email, such as: Messages that contain dangerous attachment or virus Phishing messages Messages that contain sensitive data Here’s the workflow for the “search and purge” process: Step 1: Create a Content Search to find the message to delete Step 2: Connect to the Security & Compliance Center PowerShell
Source: Search for and delete email messages in your Office 365 organization – Admin Help – Office 365
Had an issue today that I needed to delete an email sent out internally. I used this post from microsoft to quickly find and delete the emails.