Overview
When setting up your sending domain, you'll need to add specific DNS records to authenticate your domain and get the best deliverability possible for your emails.
Update your DNS information
To get your domain authenticated, go to Account Settings 
> Domains & IPs. From there, send the information to your DNS administrator or copy the fields for use in your DNS provider. To email them to your DNS administrator, select the email the full list of DNS records to a teammate option, and enter the email address of your administrator.
Once your administrator has updated the DNS records, you can return to the Domain & IPs screen and click Verify all DNS Records at the top of the table. The authentication usually takes 10-15 seconds. Once verified, the status for all the records should become green checkboxes.
If the entries do not verify, the DNS entries may still be propagating. This propagation period typically takes no longer than 30 minutes. If this period hasn't passed, please wait and try again. If you have issues with this step, please reach out to Support with questions.