It can be anything! An apex, subdomain, or even a URL.
Results forknowledge.smtp.com.00d60000000iqaeea0.live.siteforce.com
www.knowledge.smtp.com.00d60000000iqaeea0.live.siteforce.comsmtp.com.00d60000000iqaeea0.live.siteforce.comcom.00d60000000iqaeea0.live.siteforce.com00d60000000iqaeea0.live.siteforce.comlive.siteforce.comsiteforce.comcom