Suddenly a friend and I are having trouble receiving emails from each other. She uses a different service (Road Runner) than I do (Yahoo). Besides Yahoo, I have a Gmail and RR account, so I did an experiment - I sent a test message to each account from each other account. The results were that my RR sent messages were received by both Yahoo and GM. Of the two messages sent from Yahoo, GM received, but RR did not. Of the two messages sent from GM, Yahoo received, but RR did not. Maybe a flow chart would help seeing what happened (below - green are completed transmissions - pink didn't go through).
Now I'm confused - her messages from RR are not received by my Yahoo, but my RR message was and I cannot receive her RR messages in my Yahoo.
Any idea what's going on?