I would suggest you use the sql-database for such things. I don't really know what you will do with that but to send a mass-eMail to all registered users you might use the sql database and handle that with scripts. But the whole sql thingy is in development as I see. Currently anope creates tables and entries into a sql-database but does not work with it. in never versions it seems they will try to make anope possible reading the sql-database. Then you also will be able to have a webinterface to manage your account. But currenty lits music for the future ^^
