Şöyle Bir Yazı Var Sitesinde : " How can I block MJ12bot?
MJ12bot adheres to the robots.txt standard. If you want the bot to prevent website from being crawled then add the following text to your robots.txt:

User-agent: MJ12bot
Disallow: /
Please do not waste your time trying to block bot via IP in htaccess - we do not use any consequitive IP blocks so your efforts will be in vain. Also please make sure the bot can actually retrieve robots.txt itself - if it can't then it will assume (this is the industry practice) that its okay to crawl your site.

If you have reason to believe that MJ12bot did NOT obey your robots.txt commands, then please let us know via email: bot@majestic12.co.uk. Please provide URL to your website and log entries showing bot trying to retrieve pages that it was not supposed to. "