Embarqmail account problems


New Email
Hello, we have 2 embarqmail accounts. On our work computer they began sending very sporadically and then just stopped sending altogether. They go out of the outbox and into the sent box, but they never appear on the other end. Have deleted and reinstalled account no fix. Changed from wired to wirelss access no fix. Talked to embarq IT there side is working fine. CAn log on online and send from there and it goes through fine. Other computers in my house were sending fine, UNTIL TODAY. To work around the problem we started using another computer. Today half way through the day it started happening on that one. Please help as I am stumped.