Regarding mailing lists, I have a question about ethics.

I have accumulated a modest mailing list of people who have read my books etc. When I started Christian Indie Books I transferred all my names to the list for the new CIB website. Should I have kept the 2 separate? I have my books listed with 100 or more other books on CIB. I feature a blog on it, and I have also started a podcast that I may set up on a separate page there. Now I have put the writers, whose books we have listed, on my mailing list so it is easy to contact them all at once, but is it OK to send them blog announcements etc.? I don’t want to do anything that is not ethically correct.