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:

  zisman na chello.cz
    SMTP error from remote mail server after RCPT TO:<zisman na chello.cz>:
    host mxin5.upcmail.net [213.46.255.74]: 550 5.1.1 MXIN500 domain chello.cz is not hosted here ;id=bBanmgybjSwVFbBanmmTcd;sid=bBanmgybjSwVF;mta=vie01a-pemc-pmxin-pe14;d=20211015;t=030102[CET];ipsrc=62.36.20.208;
  vaseadresa na t-email.cz
    SMTP error from remote mail server after RCPT TO:<vaseadresa na t-email.cz>:
    host mail-01.rrpproxy.net [193.46.215.141]: 550 5.1.1 <vaseadresa na t-email.cz>:
    Recipient address rejected: User unknown in virtual mailbox table