Email lists are a way for people with a common interest to communicate, but always remember that when you send a message to a list, hundreds or even thousands of people will receive a copy of your message. It is good practice to follow a few simple guidelines.
Don't attach documents to the messages you send to the list. Not everyone has email set-ups which allow them to receive attached documents. And those that do know that attached documents carry the potential to carry viruses and are unlikely to read them.
On an email list, attached documents are largely a waste of bandwidth. They will more likely annoy people than help get your message across.
If you have something to say - try to include it in the text of your message, or else point to a web URL where people can find the same content.