Every webspace provider I've ever used has offered web-based mailing lists of some kind as part of the package. These are intended for discussion but can be usually be configured as 'announcement' lists (that is, nobody can reply to them) and the addresses of recipients are not displayed. If you are using 'free' space from your ISP, you won't have that option; otherwise, I should talk to whoever you rent from. The facility may already be available to you.