Malformed DNS server reply

Hello Community!

I have a mailgun account, which I have setup MX records for in Cloudflare. There are still a few errors when sending out emails, mainly: “Sender address rejected: Malformed DNS server reply”.

I have been working with Mailgun support on this, and they have said the following:

It looks like we’re still showing similar values for your MX records:

dig mg.siteurl.com MX +short
10 mxb.mailgun.org\03210.
10 mxa.mailgun.org\03210.

Can you remove the trailing “\03210” from these? Your screenshot doesn’t seem to show them, so you may need to double-check this with Cloudflare.

When I look this up in Cloudflare, it does not show any trailing numbers.

Has anyone come across this issue in the past?

Thanks!

\032” is the DNS way to encode a space. Are you sure the MX records don’t say the server is e.g. “mxa.mailgun.org 10”? It should be server “mxa.mailgun.org” and priority “10”.

4 Likes

Thanks mnordhoff - that is super helpful information. I have re-added the mx records making sure to not include any spaces, and I have deleted the old ones. I will wait for DNS propagation, and then reply if it fixed the issue.

Thanks again!

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