We will not tell you, else ppl start posting heavy stuff to increase ranks. See amiga.org: "Hey.. i have 5000 post.. look I'm soooo coool." etc.
By looking around a bit more you can guess the threshold... the lower ranks are easy to climp... buth the high ranks are very hard when you not only post useless comments. AFAIK for the hightes rank you need more than 20.000 posts . That's all we can tell you.
The first rank comes at 21 posts. To become "Order of the Butterfly," you need 151 posts. The rank that Tokai speaks of as needing the tens of thousands of posts is "Yokemate of Keyboards"