How to Configure Send Connector in Exchange 2010
Okay, so we have the Exchange 2010 server deployed. Internal mails flow works fine and you need to send mails out to other domains.
You will need a send connector to route external mails to the internet.
Here's what you are required to do:
Open Exchange Management Console
Expand Microsoft Exchange On-Premise
Expand Organization Configuration
Select Hub Transport
Click the Send Connectors tab
From the Actions pane (on the right of the screen)
Click New Send Connector...
Provide a Name to your connector
Under Select the intended use for this send connector select the Internet option
Custom: Select this option to create a customized connector to connect with systems that aren't servers running Exchange 2010.
Internal: Internal Send connectors send e-mail to servers in your Exchange organization. This connector is configured to route e-mail to your internal Exchange servers as smart hosts.
Internet: Internet Send connectors send e-mail to the Internet. This connector is configured to use Domain Name System (DNS) MX records to route e-mail.
Partner: Partner Send connectors send e-mail to partner domains. This connector is configured to only allow connections to servers that authenticate with Transport Layer Security (TLS) certificates for SMTP domains included in the list of domain-secured domains.
Click Add under Address Space and enter * for the address space.
Under Network Settings click Use domain name system (DNS).....
Ensure that the Source server already has the mail server name populated,
That enables your mail server to send out emails to external domains