This source is known to forward email
Neostrada (previously Totaalholding) supports full DMARC compliance.
See the article to configure DKIM: https://www.neostrada.nl/support/artikel/how-do-i-set-up-dkim.html
Add 'include:spf.totaalholding.nl' to your SPF record. See: https://www.neostrada.nl/support/artikel/spf-records-what-is-it-and-how-to-use-them.html