Mac Mail with mBox Mail plug in stopped sending emails????

I purchased a new iMac for my wife about 6 months ago. In setting it up for her, I was challenged with getting her legacy @msn premium email account to work with Mac Mail. After nearly pulling my hair out and a lot of begging to try and get my wife to switch to a gmail account like the rest of the world I found mBox. Problem solved. Her @msn account has worked flawlessly with this plug in and Nicholas's fix for Mail. However, 3 days ago, Mac Mail stopped sending emails. It receives them fine, but nothing goes out. I get an error stating that the smtp server could not be contacted. I have not changed any setting in my network, Verizon FIOS, or on the Mac Mail application. I can log into the @msn account through the web, so I know the problem isn't there. I have removed the account form Mac Mail, reinstalled mBox and the fix, set the account back up and the same thing continues to happen, no emails going out. While I doubt it has anything to do with it, the kids got an XBox 360 for Christmas and I have connected it to the wireless router, but we have several items on the network and it has never caused a problem in the past. However, after install the XBox, I had to reset my router as things were a little glitchy. I doubt this has anything to do with the issues I am facing, but wanted to note it just in case. Does anyone have any suggestions on how I might fix the mail so it will send. I tried the easiest route, but after 30 minutes of begging my wife to give up the account, she wore me down and back to the problem solving I go. Help, I am begging you.