I Clicked on "Standard Shield" and then on "Customize".
I went to "Advanced tab" and select "Silent Mode" and I ticked the answer Yes.
will this delete the file automatically?
I would have though it should be Silent mode with general answer No (cancel) not Yes (OK), these answers relate not to sending the file to the chest but to questions that would ordinarily be asked upon detection if silent mode wasn't enabled.
Personally my own feeling on this is you should use the default interactive action. This way you know exactly what is going on with your system. If you are getting so many warnings, that you want to automate this process, I believe you should review your security practice - filter emails at source, delete from server rather than download them, review the sites they visit, etc.
Also I don't like giving a positive answer to something I can't see, I would rather opt to Cancel.
But if it is working and you are happy it is your system.