Blocking accounts
If we detect that the security of advertisement materials is under threat, Yandex reserves the right to terminate a site's participation on the Yandex Advertising Network and block a partner account in order to protect the interests of our advertisers as well as to protect our automated algorithms that we use to detect invalid impressions or clicks.
Accounts are only blocked if a thorough analysis of the situation leads us to conclude that posting ads from our advertisers on sites registered to your account is unsafe. Blocked accounts cannot be restored.
Yandex takes the security of its placed ads very seriously, therefore we don't disclose many details about why we block partner accounts or comment on the severity of a violation or ways to rectify the problem.