Every night the list is refreshed. You cannot presume that an intended recipient will read your message quickly, or even at all. Most users have rather small disk space allocations on e-mail servers. A single message from you can consume someone's entire allocation. And a small attachment sent to a large number of users can have just as devastating an effect on the network and the servers.
Some departments offer advice on using e-mail for courses .
In addition, there is a growing set of rules for users of Penn's electronic resources that may affect how one uses e-mail lists of all types, but especially large lists. Public bulletin boards, or conferencing, is available on the Internet through a facility called NetNews . NetNews is composed of a collection of topical discussion groups. ISC operates Penn's central NetNews server . NetNews is an interactive environment that allows messages, even files of other types, to be posted in a common, topical location and retrieved by all users with access to the system.