verizon mail not working

My iPhone6 used to work fine with the verizon mail but suddenly stopped working in the past few weeks as it does not recognize the user name or password. However, i can receive mail on my mac and iPad with the same information. Have tried all the simple fixes - deleting the account and adding it, even resetting the phone settings to factory but still no luck. Suspect it has something to do with iCloud but don't know how to fix it - any thoughts?