Before using Neo, you need to verify that you own your domain. Domain Verification is a vital step to ensure that you are using a valid "From" email address and that no one else will use your domain to perform malpractices (e.g. sending emails on your behalf!)
The DNS access is required not only for Domain verification but also to configure email delivery of the domain by changing the MX and TXT records of the domain. Hence, if your domain is not verified, you will not be able to receive and send emails.
If the domain verification is not completed, a banner will appear on your email control panel with the following error message:
In order to resolve this issue, you must verify the ownership of your domain and activate email services by adding MX and TXT records. Click here for general instructions to configure your DNS records.
Once the DNS records are configured, you're all set to send and receive emails from your domain using Neo Mail and you should see a verification confirmation message in your email control panel as shown below: