My friends tell me that they have sent messages to me that I have not received. The messages bounce back to the sender. Some messages get through but are delayed as much as 18 to 36 hours. Sometimes senders will send a message to my wife and me (both @verizon.net) and only only one of us will receive it. The sender with the most problems getting their email to us has a @yahoo.com account. This has been going on for a few weeks. The problem is the same whether reading messages on webmail, my computer or my iPhone. What is the problem and how can it be fixed?