I am still getting the error message (INVALID PASSWORD) with the sync interval set to two minutes. I am using Yahoo Mail.
That is a completely different use case. It is caused by Yahoo server. We have reported this problem to their developers already but have not received any answer yet. You can workaround it as follows: Open the account settings, select the Yahoo account and disable Calendar and Contacts services.
thanks for this. disabling my contacs and calendar have stopped my invalid user/password error.