Go to Settings > Emails > Sender Email Preferences.
Click Authenticate Now → next to the domain that you want to authenticate.
Now, copy the SPF record from the pop-up that follows, and add it to your domain name provider’s (e.g. Daddy) DNS settings.
Next, copy the Host Name and Value for the DKIM record and add it to the DNS settings of your domain name provider.
Once you’ve added both the SPF and DKIM records, click Validate.