Mac Mail has stopped sending emails at home...but can at work? On MBP 2010 Snow Lep

Why might this be happening? It can't connect to the outgoing mail server for hotmail when at home. I didn't change anything, it just did it. Odd thing is, if I go into work with my MBP the mail can send but not receive. So to get my mail I need to be at home and to send it i have to go to work. It's not the server addresses I've checked with hotmail. I've gone through the apple help online and it just sends me to a list i should ask my ISP. Not really a good answer as it's not the ISP, or hotmail, it's Apples Mail. I know this cos I take it into differnt places, different ISPs. Same thing happens. IT IS MAIL, but nobody knows why?

Been at this for a week with no idea what the problem is.

Should I just reset Mail? I don't really know how this is done but it's not the best solution....or is it? 🙂

MBP 13" 2010

Snow Lep