The search filter is set as described in my initial comment. First I tried to search for 'Hermann' in 'Sender', which does not work. Then I tried to search for 'Dank' in 'Subject', which works.
The search filter is set as described in my initial comment. First I tried to search for 'Hermann' in 'Sender', which does not work. Then I tried to search for 'Dank' in 'Subject', which works.