It can be anything! An apex, subdomain, or even a URL.

Results forwww.mail.serviceobjects.com

Logged At	Not Before	Not After	Common Name	Matching Identities	Issuer Name
2018-02-02T18:33:52.622	2015-04-29T19:14:38	2017-04-30T18:05:49	mail.serviceobjects.com	www.mail.serviceobjects.com	C=US, ST=Arizona, L=Scottsdale, O="GoDaddy.com, Inc.", OU=http://certs.godaddy.com/repository/, CN=Go Daddy Secure Certificate Authority - G2
2017-12-16T22:09:28.361	2017-04-25T20:31:00	2019-04-30T18:05:49	mail.serviceobjects.com	www.mail.serviceobjects.com	C=US, ST=Arizona, L=Scottsdale, O="GoDaddy.com, Inc.", OU=http://certs.godaddy.com/repository/, CN=Go Daddy Secure Certificate Authority - G2
2014-07-15T11:55:22.055	2014-07-08T00:42:17	2015-04-30T18:05:49	mail.serviceobjects.com	www.mail.serviceobjects.com	C=US, ST=Arizona, L=Scottsdale, O="GoDaddy.com, Inc.", OU=http://certs.godaddy.com/repository/, CN=Go Daddy Secure Certificate Authority - G2