You can easily create a new rule for an email's subject and sender when viewing the email in the detail view.
How to create a new rule for the subject and the sender:
Select an email.
Click the Create new rule window opens.icon in the detail view. Click on . The
Enter a rule name. You can adjust the conditions.
Set an action.
In order to save the rule, click on.
To save the rule and apply it to existing emails, click on. Select the folder containing the emails to which the rule should be applied.
Parent topic: Using Email Filters