I sent a private message to another user about deleted posts and minutes later several dozen of my posts were deleted by the 'administrator'.
And does that mean that they read your messages? This means that the dozen of your posts are against the rules. Would you mind telling us what exactly you told them “about deleted posts” that made you conclude they're spying on you?
Be careful with any private messages you send on this forum.
If you feel your messages are sensitive, you should encrypt them. The forum says that your personal messages' privacy isn't guaranteed.