 smtp; 450 4.1.1 <zsbolevec@pilsedu.cz>: Recipient address
    rejected: unverified address: host mail.pilsedu.cz[/run/cyrus/socket/lmtp]
    said: 550-Mailbox unknown.  Either there is no mailbox associated with this
    550-name or you do not have authorization to see it. 550 5.1.1 User unknown
    (in reply to RCPT TO command)
