Try this:
- Create a New email and add the scammer’s address in the To field.
- Right-click on the address and select “Edit Contact”. This will open the contact where this emails is stored inside eM Client.
- Once the contact window is open, click on the three lines menu at the top left (I’m on Windows) >> Contact >> Delete.
- Create a new email and check if the address still appears in autofill.
Please confirm if it works.