Fw: Undelivered Mail Returned to Sender

I tried to respond to an email to the maintainers mailing list this morning.
But the mail bounced back with the message below.

To me, this looks like either an error in how dreamhost forwards the message to the gnu email address (more likely). Or an error on the gnu side rejecting a message that it shouldn't (less likely).

Did something change with how mails are forwarded from [email protected] to [email protected]?

Markus

> Gesendet: Freitag, 10. Juli 2020 um 08:43 Uhr
> Von: "Mail Delivery System" <[email protected]>
> An: [email protected]
> Betreff: Undelivered Mail Returned to Sender
>
> This is the mail system at host pdx1-sub0-mail-mx70.g.dreamhost.com.
>
> I'm sorry to have to inform you that your message could not
> be delivered to one or more recipients. It's attached below.
>
> If you are a current customer of DreamHost, please contact our
> technical support team here
>
> https://panel.dreamhost.com/support
>
> If you are not a customer please use our contact form at.
>
> http://dreamhost.com/contact
>
> If you do so, please include this email in your support ticket. You can
> delete your own text from the attached returned message.
>
>                 DreamHost Email Support
>
> <[email protected]> (expanded from <[email protected]>): host
>     eggs.gnu.org[209.51.188.92] said: 550-[SPF] 64.90.62.164 is not allowed to
>     send mail from gmx.de.  Please see 550
>     http://www.openspf.org/Why?scope=mfrom;[email protected];ip=64.90.62.164
>     (in reply to RCPT TO command)
>