Let's assume you've come to know that users in organizations similar to yours are receiving bulk marketing emails that could be spam. You also learn that these emails usually have the word "lottery" in the subject line. 

Customizing the Mail Search reports:

To identify these messages, you need to create a new report using Exchange Reporter Plus. To do so,

1. Go to the Reporting tab.
   
2. Click the Create New Report button.
   
3. Enter the Report Name.
   
4. Choose Mail Search from the Select Report Type drop-down menu.
   
5. Select the mailboxes whose messages you want to search through.
   
6. Use the Filters option to filter based on folders, keywords, and attachment size.
   
7. Click Create.
   

Once you click Create, Exchange Reporter Plus creates a new report that shows the data you require once the scheduled data gathering task ends.