Most of my emails aren’t send anymore. I got this reply:
Mail delivery failed: returning message to sender>
>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 failed: ...t-online.de
The support of my provider told me, that my IP address (be sent over VPN) are marked as spam because it is on 4 black lists.
>--- The header of the original message is following. ---
What should I do?