The message looks like spam
If you sent a message from a Yandex address and received a non-delivery report that states: “Message rejected under suspicion of SPAM”, “Message rejected as spam by Content Filtering”, “ Message rejected. See http://mail.google.com/support/bin/answer.py?answer=69585 for more information”, “Sorry, message looks like SPAM to me”, “550 5.7.1 SPF check failed: <IP_host> is not authorized to send in the name of <domain_name>. (in reply to RCPT TO command)” this means the recipient's mail server treats your email as spam.
Try contacting the recipient or his/her mail service administration by another method and report the problem.
If you are sending legitimate messages to your website users or subscribers, please read Yandex requirements for honest mailing lists.