This is the mail system at host mailout08.t-online.de.

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                   The mail system

<xxxxxxxx@Gelöschter Nutzer.com>: host mta7.am0.yahoodns.net[67.195.204.72] said: 421
    4.7.0 [TSS04] Messages from 194.25.134.20 temporarily deferred due to user
    complaints - 4.16.55.1; see
    https://help.yahoo.com/kb/postmaster/SLN3434.html (in reply to MAIL FROM
    command)