Hi @Federico Coppola ,
- Based on my knowledge, when you send mail, if there is an applicable send connector in the Exchange organization, it will be used and sent by default.
- Have you tried to send a test email and see if it can be sent successfully and the recipient can receive it? If the recipient did not receive the mail, you could run the first command line below to view the transport queue information. If you see message stuck in the queue for the next hop domain, you could run the second command line below to check the "LastError" attribute of the queued messages, which will often contain a status code that will tell you why the message are not being delivered.If there are any errors, please share with us, it should be that hide your private information. Get-queue
Get-queue | Get-Message | fl
3.You could following the steps to create a send connector in Exchange 2010.
- Open Exchange Server Management Console and Expand the Organization Configuration node from the left side pane.
- Click Hub Transport, and then click the Send Connectors Tab,right-click Hub Transport and select New Send Connector.
- The New Send Connector wizard will open on the Introduction page, you will need to give the Send Connector a name and then select its type.
- On the Address Space page,Configure the destination domains that the Send connector is responsible for.
- On the Network Settings page, Configure how the Send connector routes mail: by using DNS or by automatically forward all mail to a smart host.
- On the Source Server page, your Hub Transport Sever will be automatically selected.
- Finally you will successfully create a send connector.
For more information you could refer to : How To Create a Send Connector in Exchange Server 2010
In addition, Exchange 2010 will end support on October 3, 2020. I suggest you upgrade Exchange Server to a higher version as soon as possible.
For more information you could refer to: Exchange 2010 end of support roadmap
If the response is helpful, please click "Accept Answer" and upvote it.