Sender address rejected: Domain not found

Hi @copleykj 👋
 

Aaron here from the Customer.io support team. Thanks for reaching out to us here!

Jumping right in, the bounce reason that you’re seeing is indicative that there is an issue with your domain’s DNS settings. Sure enough, if we look at the DNS records for your domain, we can see that the MX and SPF (TXT) records are missing. They were there at one point, which allowed your domain to be verified, but they have since been removed by someone in your organization that has access to your DNS hosting account (Google Domains).

MX and SPF (TXT) missing:  https://www.nslookup.io/domains/cio94253.wcona.com/dns-records/

DKIM (TXT) still present: https://www.nslookup.io/domains/krs._domainkey.cio94253.wcona.com/dns-records/ 

So, to provide clarity, Customer.io only checks for your DNS entries when you click “Verify domain”… there is not continuous polling to check that the records are still in place. You can get this issue sorted quickly by adding those MX and SPF (TXT) records back in Google Domains. The values for those records are:

MX Record:

• Type: MX
• Hostname: cio94253.wcona.com
• Value: 10 mxa.mailgun.org
• Value: 10 mxb.mailgun.org

SPF Record:

• Type: TXT
• Hostname: cio94253.wcona.com
• Value: v=spf1 include:mailgun.org ~all

Once you get these records added back in Google Domains, your domain with be properly authenticated again and you should see these bounces resolved. Please don’t hesitate to reach out if you have any further questions!