It may just be a case of waiting if you set the mail account up recently. Sometimes several hours or sometimes minutes.
The support check you did would have shown resolved because it is testing the server is up locally.
Your mail addresses IP numbers appear okay from the UK have you checked locally from your own machine?
Double check you have the correct username or mxxxxxxx entry together with your password which of course is case sensitive. That is that if it is xFxB then you enter xFxB not xfxb etcetera.