unable to sign in to USPS.com and informed delivery

I'm trying for weeks to sign in to inform delivery to find out if I have mail and have been unable to do so The mobile app and USPS.com do not work I also called USPS 800 number and the girl said she doesn't know why and could not help me either would be nice if it would be fixed I've had problems with my mail delivery at times and it would be nice to be able to see what I'm really supposed to get in my mailbox each day Thank you so much in advance