Update SPF Record for Deliverability
In most cases, the CartStack mail sending domain(s) are proficient for a high-deliverability rate, but if you are noticing issues (eg: live emails going to spam folder), you can try adding an SPF record to your web site's DNS settings.
In this example, we'll say that your domain is "website.com". If you don't already have any SPF records for your domain you will add a new one. Here are the details you'll need:
Host: @ or website.com
Value: v=spf1 include:mailgun.org include:m1.cartstack.com ~all
v=spf1 include:website.com ~all
v=spf1 include:website.com include:mailgun.org include:m1.cartstack.com ~all