As well as using SPF, DKIM and SenderID, you can also use the DMARC authentication process to optimise your delivery rates. The only prerequisite is that you use your own dedicated IP. In addition, a subdomain has to be allocated to your domain. Only when this is done will it be possible to build up a reputation and place the relevant records into your DNS settings.
If you are already using your own dedicated IP from Newsletter2Go, please contact our support team so that we can set up the DMARC authentication for you. If you do not yet use your own dedicated IP for your newsletter dispatch, learn more about this here. Just speak to us. We would love to help and advise you.