To do it well there are two important steps that I mention here to complete Chris's information. To do so, go to "my account".

1. Is about security, you need to validate your domain name AND your sending email addresses. If you do not do this, you will receive a notification that an unvalidated email address is trying to send email.

2. Not required but recommended.

To improve your sender reputation and deliverability, we strongly recommend that you set up a few DNS records.
This will allow us to sign outgoing email using DKIM and DomainKeys, and will inform your contacts' email providers that we are allowed to send your emails