This is where we "define" what happens on the mailing list.
In general, spam (messages that are from people not subscribed to the list, and that has nothing to do with the topic of the list) is dropped without a return notice. (Providing a reason seems to incite more spam - frequently from different spammers).
Messages coming from subscribers and that's not linux related is politely rejected with a reason (off-topic, off-color, or not germaine to the list).
If the message has anything to do with Linux or the purpose of the list is generally accepted.
Note that moderators should reject only non-linux related posts, and illegal activities.