You keep marking it as Spam whenever it gets to the Inbox folder. Junk mail is an endless battle. You should find these of interest----------------
My opinion an "email expert" should be able to recommend a spam filter
There is no spam filter to "recommend". There is the filtering system Comcast uses. You can check your account settings to see if you have it enabled. On the Inbox page click on the gear icon in the upper right corner, then on Settings. Under Advanced settings on the landing page look to see if the box is checked to enable the Spam filters.