Hello @loft,

Welcome to the Klaviyo Community!

If you haven’t already, I would encourage you to take a look at our How to change your sender email address Help Center article. Using a sending address whose domain is from a free email address provider does raise suspicions from inbox providers and are likely to be blocked/bounced.

For this reason, the best domain you can use for your sending address is a professional one that aligns with your brand. This will indicate to inbox providers that you’re a legitimate business. For example, something like CustomerService@YourBrand.com. 

I hope this helps!

David