yahoo email won't link to iphone 6

why won't my yahoo email link to my iphone 6? it was linked and one day it asked me to update password by logging in. After entereing my password it would refresh and time out every time. I deleted my email and have been trying to add it ever since. It will recognize my password but fail to connect to my mail. I have done it through settings and with the bottom mail button. It says i have successfully logged in and once I push continue to finish it continues to refresh with out finishing the pairing. I have done a soft boot with no difference.