I only get this error on one specific email account with Comcast. When The Bat does it's email check, it returns the following error message:

Connection to host broken (last commands sent were: "UIDL", "TOP 1 0")
I looked up UIDL and it says it's some kind of extension that most, but not all POP3 servers support. So does this error mean that my POP3 server is suddenly no longer supporting this extension?