It will only work if you "Always" "Accept third-party cookies and site data". Choosing "From visited" will block gmail but still allow Hotmail and Yahoo Mail. No help on the website for this, I figured it out by trial and error. Spent months without X-notifier thus 3 stars.
app stopped working 6 months ago only shows notifications to last email account opened all the other email account do not show (all accounts are are with outlook.com ) support has not responded in 2 weeks