New email domain - SMTP 550 5.7.1 Unable to relay

Question

I have just added MX record for mail.example.com. Previously there was MX record for example.com. we have default email address-domain @example.com - and it is working fine for send and receive. we need to get some admin-level email addresses working that ends with @mail.example.com, for example:

• [email protected]
• [email protected]
• [email protected]
• [email protected]

so we added the MX record and pointing to same server. I tested sending email to [email protected] and [email protected] from inside domain and I am able to receive emails to them. but from outside, I am not able to send email to those address. it says

Message not delivered
Your message couldn't be delivered to [email protected] because the remote server is misconfigured. See technical details below for more information.

The response from the remote server was:

550 5.7.1 Unable to relay

now, i see there are some suggestion to create new receive connector in Exchange. we have Exchange server 2013. what parameters I need to use to create the new receive connector? we already have default receive connector in both exchange servers for example.com and both inbound and outbound emails are working fine.

we have two exchange servers 2013, the servers are on cluster. each server has its own receive connectors as below.

Client Frontend <server-name> - FrontendTransport
Client Proxy <server-name> - HubTransport
Default Frontend <server-name> - FrontendTransport
Default <server-name> - HubTransport
Internal-Relay <server-name> - FrontendTransport
Outbound Proxy Frontend <server-name> - FrontendTransport

any suggestion will be greatly appreciated. thanks.

Answer 1

You don't need a new Receive Connector at all. Receive Connectors have nothing to do with the domains that the server can receive.

The only thing that you need to do is add the domain to the list of Accepted Domains. mail.example.com and example.com are different domains as far as Exchange is concerned.

Once you have added the domain to the list of Accepted Domains, add the email addresses to the various accounts as required. For a small number of addresses I don't bother with email address policies.