What does everyone use to send out newsletters, email campaigns?
dbc: I don't have any advice for software to use, buy I do suggest you use something other than your production DNS domain and mail server for sending out these messages. Even if all of them opt-in, some of your recipients will mark your messages as spam and that mail server/domain will start to show up on blacklists. If your production domain is xyzcorp.com, maybe you should register xyzcorp-messages.com for this activity.