Bitpost 0.9.8.3 for Mac can be downloaded from our website for free. This free Mac app was originally created by Voluntary.net. Bitpost for Mac is included in Communication Tools.
From the developer:
Bitpost is a user friendly Bitmessage client for OS X. Bitmessage is a decentralized messaging system. Instead of connecting to centralized servers (like Facebook, gmail, etc) or federated servers (like email, IRC, Jabber), when you run a Bitmessage client it connects to other clients directly forming a network which can relay messages with no central control.
You may want to check out more software for Mac, such as MySpaceIM, ISL Pronto or Instant Messaging, which might be similar to Bitpost.