@Belcanto
Ha, we are talking past each other. 🙂
If you want delete mails from one sender click on the Options button.
Select "From".
Now all mails are sorted by sender.
Select the first mail you want to delete, hold the Shift key and select the last mail.
Use the delete button to move them to the trash.
Go to the trash section, click on the Select button.
Select "All".
Use the delete button again.
You can try to use the search field for the sender name, hit return to start the search and then select all, delete.
Cheers, mib