I created a new txt record, with this:
v=spf1 mx a include:_spf.perfora.net include:_spf.kundenserver.de include:servers.mcsv.net include:mout.kundenserver.com ~all
And deleted the SPF record, do I have to change something else in txt record?
Now I got a “PASS” spf in gmail with this, but don’t know if I should change something in actual txt record.
The record is failing validation because there is no policy for mout.kundenserver.com. Once that is removed the record will probably validate successfully.
What goes in your SPF is directly related to the IP addresses and services that you send email from, so only you can reliably write a good SPF record. You should include only those hosts that you send mail from. You should investigate DKIM and DMARC also, as combined with SPF they are designed to ensure that only your authorised email servers can send email that claims to come from your domain.
A service like https://dmarcian.com is useful in gathering reports and gradually increasing the authority of your email domain.