diff --git a/lib/nntp/tiny/session.py b/lib/nntp/tiny/session.py
index 014d18b..ab79c99 100644
--- a/lib/nntp/tiny/session.py
+++ b/lib/nntp/tiny/session.py
@@ -741,7 +741,8 @@ class Session():
     }
 
     def greet(self):
-        return self.respond(ResponseCode.NNTP_SERVICE_READY_POST_PROHIBITED)
+        self.respond(ResponseCode.NNTP_SERVICE_READY_POST_PROHIBITED)
+        self.flush()
 
     def handle_command(self):
         line = self.readline()