I have three established working gmail independent address that work fine on my apple devices. On my windows T Bird desktop, every time I try to send an email a window opens and demands credentials for the acct ( name password etc) BUT it will not allow me to enter them???? When I close the window the email appears to be sending but, despite showing up in my sent file, some emails do not send. Obviously a T Bird problem which is making me crazy!!!! Any suggestions PLEASE!@!!!