Sbcglobal.net email login problems - Not found on Accelerator

I am helping my husband fix his log in to his sbcglobal.net email account.  We are able to enter his email address. But the next window we get is "Not Found on Accelerator.  Description: Your request on the specified host was not found.  Check the location and try again."  What does this mean and how do I fix this problem?