I got the following answer when tried to send test to Timus team:
   ----- The following addresses had permanent fatal errors -----
judge_mailbox@busin.usu.ru
    (reason: 550 5.1.1 User unknown)
    (expanded from: <timus_support@acm.timus.ru>)

   ----- Transcript of session follows -----
550 5.1.1 judge_mailbox@busin.usu.ru... User unknown

I have received your message. But one of the other recipients had a problem with his mailbox. This mailbox is  fixed now.