My internet access provider is att.net. I am there because they offer the cheapest rates. As it turns out they subcontract email services via a pop3 server on Yahoo.com.
This means when I download via Outlook my email, say from LBO. what really happens is yahoo.com handles the account @att.net.yahoo.com, by logging into the pop3 server at yahoo. The point is that att.net doesn't handle any email.
Well so what? Worked fine until sometime in the night of July 30 pst.
As far as I can tell yahoo changed their terms of service, which you had to manually accept. They must have enterly forgot their one of their biggest accounts was with att.net which is automated. There is no way to get a pop-up screen or warning or simple way to accept the new TOS agreement back to the user. All that's on the other side is an att.net server that passes on the username and pwd to pop3 server. The pop3 server accepts the username and pwd and responds with a request to accept new TOS agreement. If a real person had logged in, they would see a text screen with this info and a box to check and hit enter. Then the connection would be established.
If there is only a server at the other end, there is no answer, or maybe a re-login attempt. Authentication fails, and an error message is generated and passed back to the original user's email account where it appears as a failed login or bad userid/pwd.
As far as I know Yahoo.com uses some version of unix for its mail system. It is very simple to change the perameters of the login screen in server to sever communication. It's done with a configuration file.
I wrote such a file for the ancient fetchmail. It follows some standard (pop3) protocol, which I have entirely forgotten. The key issue is the config file has to correspond exactly to the protocol of the server contacted.
It goes like this. I contact a server by DNS name (or its numerical address) directly from a command line (forget the command). I get an answer, LOGIN. I send userid. I get an answer, PASSWORD, I send the pwd. I get answer LOGGED IN. Or DENIED. If there is any unexpected intermediate step, the sequence fails. The script fails and I am DENIED access.
I suspect whatever idiot decided to insert a TOS step in this sequence or whatever was the normal sequence, broke the entire pop3 communication system at Yahoo.
According to news reports this effected 300 million users.
Now I am at gmail which has a suck-u interface.
CG