My hotmail account appears ‘Offline’ and won’t send messages from my MacBook even though I can receive them.

When I use the mail application on my MacBook, I can receive emails however when I try to reply to them, it says that there is a server issue as my hotmail account is 'offline'. When I go on to my preferences and opened up the advanced settings, it appears that the SMPT (The outgoing mail server) is offline and the POP(incoming mail) is working fine. I have tried both selecting and unselecting the SSL check box, re-entered my password and I have also deleted and re-added the hotmail account to my mail app. When i log on to outlook.com both servers work fine and I am able to send emails from here so I am at a bit of a loss to why they wont send from the Mac Mail app.