Lists enable a large group of people to exchange messages on a common topic.
Any member of the group can send a message to the group and a copy will be sent to everyone else on the mailing list. Standard usually means that you will receive a separate e-mail for each posting to the list. Digest mode means that you will receive an e-mail that includes messages grouped together. Digests are only compiled and sent out once each day unless the volume of messages is large. In Standard mode, you receive each message as it is sent.