Error server and configuration SPF

Hello everyone
I have a problem with the configuration of the plugin Mailpoet.
The emails are sent but a lot of them are in spams. So I would like ton configure the SPF because I had a message about this in mailpoet.
I choose “MailPoet sending service” in the configuration and I have this :
mydomain.fr 3600 IN TXT “v=spf1 include:_spf.kundenserver.de include:spf.sendingservice.net ~all”
in IONOS (ex 1&1) server.

And know, Mailpoet display this erreor :
The e-mail could not be sent due to a technical problem with %1$s: An error occurred while processing the request, the server returned the response code 200

How can I fix it ?
Thanks for response.