Thank you for reaching out and posting this question.
It looks like you may be using a third-party domain, and you’ll need to add Shopify’s CNAME and DMARC records in order to send emails using your branded email address. Due to recent changes with Gmail and Yahoo, you’ll need to follow our guide, Authenticate your third-party domain, in order to resolve this issue. If you require further assistance with this task, then this is something that your domain provider can assist you with.
If you have any other questions on this topic, then don’t hesitate to let us know.