windstream email error

Is receiving mail the only time you notice this behavior? If so, you can go into the mail account and check the incoming mail settings to ensure they are correct. Also, make sure you have a good data connection, either wifi or cellular. When you see this error about verification, are you always on wifi or cellular when this happens, or does it not matter how you are connected?

Okay, that information helps. Are you using a POP account, that both of you are accessing with your phones? Do you check this mail with your computer as well? When the mail client checks mail with a POP account, it does not necessarily release it immediately, and that can cause the "in use" error.

Again, check the incoming mail settings in the mail account as suggested earlier.