When http:// or https:// is left out of the URL field in email blasts, NationBuilder automatically prepends email blast links with a control panel URL path. If the control panel user clicks on that link in the email previewer, they are redirected to a 404 error. When the URL entered begins with www, NationBuilder will prompt the user to add an http, but canceling that prompt will still result in a broken link.
For example, if I had a link to "example.com" in an email blast:
It will update the mailing link and include a reference to the location of the email blast in the control panel. Ex: https://slug.nationbuilder.com/admin/broadcasters/1/mailings/122/example.com
When the email is sent, the recipient link can access the original link at "example.com." However, this link is not encrypted, so clicks are tracked and UTM tags are not applied for analytics tracking.