Bounce unwanted e-mail back to sender

Hi, I’d like to create a filter which will bounce mail back to the sender to the effect of “user unknown” or similar. How do I go about this? I don’t find anything under FAQ or other topics.

Unfortunately we don’t offer that option.

If this is from a list you have previously subscribed to, there should be an option in the message to unsubscribe.

But if you are trying to bounce unwanted spam, all that will do is confirm to the spammer that your email address is in use, and your address may be sold to other spammers as a verified active address. Best is just to delete the message.

Thanks, Gary, I appreciate your quick response. and detailed reply.