Hey @GymFlo Coaching 

Mail servers use email authentication protocols to verify that incoming emails are from legitimate senders, protecting your brand and your customers from malicious actors. The most commonly used email authentication standards are SPF, DKIM, and DMARC.

If your emails fail this verification, it can cause your emails to be rejected or to be placed in spam. Determine if your brand is using a DMARC policy and make sure that it is valid.

In order to be DMARC compliant, you need to connect a branded sending domain (also known as a dedicated sending domain) to your account where the root domain of your DSD matches that of the root domain used in your sender email address (friendly-from address). For instance, if you send an email using sales@example.com as the from address and example.com is protected by DMARC, your account will need to use a branded sending domain like send.example.com to meet DMARC requirements.

In addition to preventing phishing and spoofing attempts, implementing these protocols can help improve deliverability, as mailbox providers will be able to confirm the identity of the sender. 

You can also read more about it here

Let me know if this fixes your issue. if the issue still persists, I would suggest you reach out to klaviyo support via email or chat here

I hope this helps and thank you for posting your question here in the community,

Cheers

Arpit Banjara