Mail delivery failed: returning message to sender

[Mail Delivery System]

This message was created automatically by mail delivery software.

A message that you sent could not be delivered to one or more of its
recipients. This is a permanent error. The following address(es) failed:

  davidof9 na gambrinus.cz
    SMTP error from remote mail server after RCPT TO:<davidof9 na gambrinus.cz>:
    host mx.vshosting.cloud [93.185.99.201]: 550 5.1.1 <davidof9 na gambrinus.cz>:
    Recipient address rejected: undeliverable address:
    host 10.3.13.225[10.3.13.225] said: 550 5.1.1 <davidof9 na gambrinus.cz> User doesn't exist:
    davidof9 na gambrinus.cz (in reply to RCPT TO command)
  bohac na lom-hlinsko.cz
    SMTP error from remote mail server after RCPT TO:<bohac na lom-hlinsko.cz>:
    host ns.airnetdt.cz [91.221.2.254]: 554 5.7.1 Service unavailable; Client host [62.36.20.210] blocked using bl.spamcop.net; Blocked - see https://www.spamcop.net/bl.shtml?62.36.20.210