Move your mouse to the top of their post (where the username and time of the post is located). A shield icon and the word "Flag" appears. It is a pull-down menu that allows you to Ignore User or Report Abuse.
On that top line, after the posters name and how long ago the post was hover and a "flag" thingy will pop up. Here if you're setting on a post from that posted click ignore (or report abuse if SPAM), or both.
However when I got home late last night and the past few days atleast for me the ignore wasn't working and the MB was full of poo.
I have had one ear on the call starting half way thru. Premarket looking decent.