How can I prevent an external object from rejecting emails from a test server?

Question

I am currently working with a client that allows users to create emails that are sent to the client’s mail server where they are parsed, a language of content is added, and they are resent to the recipient.

So my server basically sends the following:

FROM: [e-mail] TO: [e-mail] SUBJECT: hello world BODY: |FROM: [e-mail] |TO: [e-mail] |CC: [e-mail] | Dear so-and-so. Here is the information you were asking for. Sincerely, Anyone. 

When these emails are sent from our website (i.e. www.myserver.com ) to our SMTP server, they pass smoothly.

However, when I try to send it from our testing sites (i.e. test.myserver.com ), they are rejected with the following information:

 #5.0.0 smtp; 5.1.0 - Unknown address error 550-'rejecting spoofed message' (delivery attempts: 0)> #SMTP# 

Is there any way at our end for these emails to go through, or do we need to ask an external client to reconfigure them so that we can send emails from other subdomains?

Answer 1

it must be the recipient’s domain to make changes.