Rambox is great to keep an eye on every Chat-Client, Mailservice etc. However the free community edition doesn’t feature an AdBlocker. To hide the very infuriating ads in Outlook do the following:

Click on the Rambox logo in the upper right corner, then next to your Outlook service the settings gear. Now expand the extra settings and copy the following code in there:

function applycss(css){
    var head = document.getElementsByTagName('head')[0];
    var s = document.createElement('style');
    s.setAttribute('type', 'text/css');
    s.appendChild(document.createTextNode(css));
    head.appendChild(s);
 }
applycss(`
#skype_container, .pBKjVBVDRKIDHWS0A95I, .OUTBRAIN, .O3eUZdnmMvkIwt1YXEL4, .VPtFloqixpkkqJNcOv2T {
    display:none !important;
}
`);

Reload Outlook and you are ready to go.

If this code won’t work in the future, open Outlook in your browser and find the div class wich contains the ad and replace _3_hHr3kfEhbNYRFM5YJxH9 with your class.