On The Use Of Multiple Company Mailing Lists

DippyOz asks: "We have a debate raging at work about mailing lists that I hope the Slashdot community can shed some light on. I would like to have three or four internal mailing lists with each having a very focused topic and rules. Our staff can join whichever lists they feel they need to join to do their daily jobs. Our IT manager is against this, preferring the one general mailing list to which all staff subscribe. No list will have very high traffic, as they will mostly be used for company and software announcements. Which would be better?" Although this is highly subjective, I think this is an interesting question. Could those of you who work in companies that use mailing lists comment on what has and hasn't worked for your offices?