Why one domain domain breaks SPF under ms365

We are currently using Klavityo for marketing emails and have custom send domains. When the email is logged under Klaviyo source in dmarcian, it is all green.

When logged under MS 365, it is showing breaking SPF. Any ideas why?

Hello xrsean,

This is often the case when forwarding has occurred. More specifically, the messages that originated from Klayvio, were delivered to recipients in your ‘list’ as planned, but that in a small number of cases, those recipients relayed those messages to another destination. We do our best to classify this message path in to the ‘Forwarders’ tab, but don’t always get it perfect.

The advice here is to simply ensure you are reliably DKIM signing through Klayvio, using your domain. You have achieved that here. What recipients do with your message after you hit send is a bit out of your control.

I hope this answers your question.