exim

These are just some Exim command line arguments that I use all the time but can never remember the finer details of.

Cancel a message in the queue, informing the sender via bounce message, and also silently delete a message from the queue:

There are a number of times when a domain is being used for something else other than web sites and emails. It should never send email, nor should it ever need to receive it because it does not generate abuse.

Telling everyone else about your choice never to send email from this domain means that it has less chance of being abused in a Joe Job, and you have less to worry about when it comes to that domain. It might even save a few people on the internet from seeing a couple more spam messages.