Einrichtung Portweiterleitung für Synology

This is the mail system at host ******.

I'm sorry to have to inform you that your message could not
be delivered to one or more recipients. It's attached below.

For further assistance, please send mail to postmaster.

If you do so, please include this problem report. You can
delete your own text from the attached returned message.
                   The mail system

<*******@googlemail.com>: host    gmail-smtp-in.l.google.com[74.125.143.27] said: 550-5.7.26 Your email has    been blocked because the sender is unauthenticated. 550-5.7.26 Gmail    requires all senders to authenticate with either SPF or DKIM. 550-5.7.26    550-5.7.26  Authentication results: 550-5.7.26  DKIM = did not pass    550-5.7.26  SPF [******] with ip: [*******] = did not pass    550-5.7.26  550-5.7.26  For instructions on setting up authentication, go    to 550 5.7.26  https://support.google.com/mail/answer/81126#authentication    4fb4d7f45d1cf-5c93730358fsi3915370a12.623 - gsmtp (in reply to end of DATA    command)

Fehler bei der Nachrichtenzustellung an folgende Empfänger oder Gruppen:
********
Die Nachricht wurde nicht zugestellt, da sie vom E-Mail-Anbieter des Empfängers zurückgewiesen wurde.




Die folgende Organisation hat Ihre Nachricht abgelehnt: mx00.ionos.de. (********, the server for the domain ********.).




Diagnoseinformationen für Administratoren:
Generierender Server: googlemail.com


*********
mx00.ionos.de. (*********, the server for the domain *********.)
Remote server returned '554 5.7.0 <mx00.ionos.de. (*******, the server for the domain ********.) #5.7.0 smtp; 550-Requested action not taken: mailbox unavailable 550 For explanation visit https://postmaster.1und1.de/en/case?c=r1601&i=ip&v=209.85.208.51&r=1MsKrq-1tnjhe1SYc-00vyqf>'