My NC and mail server are on two different Cloudrons. I had to go into the NC Admin Settings --> Administration --> Additional Settings, and log in as SnappyMail admin through the link on the page and did the following:
Domains: add your domain(s) to the list
Click on your newly added domain and enter your mail server under IMAP and SMTP.
Go to Security and change the default admin password.
You should be able to log in now.