Difference between refuse mail and do not deliver mail

Question / Problem

What is the difference between the Exchange Server Toolbox rule actions "Refuse mail" and "Do not deliver mail"?

Answer / Solution

Refuse mail is only available for incoming (recieve) emails. This means that the Exchange Server is currently recieving the email but has yet to accept it. The rule action allows to refuse to accept the email and return an error message to the sender.

Do not deliver mail does not depend on the current status of the email. The rule action will have the Exchange Server quietly discard the email without delivering it.