Redmine

Hi,

we installed Redmine with Bitnami in Windows and can't set up email notifications. I am trying to edit the file C:\Bitnami\redmine-4.2.3-3\apps\redmine\htdocs\config\configuration.yml

default:
email_delivery:
delivery_method: :smtp
smtp_settings:
address: "localhost"
port: 25
authentication: :none
but get an error:

An error occurred while sending mail (No connection could be made because the target machine actively refused it. - connect(2) for "localhost" port 25)

We are using the Microsoft Exchange server. Can anyone help me to properly set up email notifications in Redmine?