I am having the same problem. I've tried changing my password, deleting and adding back the account, deleting emails and folders on webmail and no change. Please help.
I am using Motorola Droid Razr Maxx, Android 4.4.2
Exact error message is "Error Synchronizing mail: Network Error"
I have two yahoo accounts, one gmail and one hotmail. I am only experiencing this error on ONE of the Yahoo accounts.