Our newsgroup is accessible via Google Groups as well, and you can post to alt.astrology.moderated if you have an account with Google.
LinkedIn has several forums for people interested in astrology. You can find those I am a member of at this link: se.linkedin.com/in/kjellpettersson/
I recommend in particular OPA, Organization for Professional Astrology, though I believe it is open only to professional astrologers so if I remember that right one would need to qualify to be a member. LI itself probably has a real name-policy, but they seem to be lax with it.
Though not exactly a forum, and I am also not exactly myself that active there now, there is also quite a lot of astrological activity on Twitter. I follow primarily astrologers and people with a high quota of related content, so if that is also of interest you could check out those I follow:
(It is possible there is a direct link to a tab with only those I follow, but I cannot find it.)
Also not a forum, but still with some interesting content relating to astrology, is Quora (quora.com
). Cave canem, though, as there are a lot of quite hostile skeptics there. The site has a strict real name-policy.
Google Plus and Facebook also have groups of various kinds, too many to list here. I cannot right now find a way to list those I am a member but should there be interest contact me on the sites in question and I'll respond. (All my social media presences are available via my homepage, kjellpettersson.com
.) Both G+ and FB claim to have real name-policies, but they are not that strict with them it seems.