I recently ran into an issue at work where users were having some difficulty changing their passwords via OWA. We just rolled out Exchange and are setting new users up, so it’s pretty important that they be able to reset their passwords after initial setup.
It turns out that OWA can have some difficulty with the Minimum Password Age policy on domain controllers. By default, this is set to one day. Users attempting to change their passwords on the same day that their Exchange accounts were created will be greeted with an error stating “The password supplied does not meet the minimum security requirements. Please contact technical support for your organization if you need help.”
You can read a bit more about the issue in the links below: