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

Results foremailservice.ws.symantec.com

Logged At	Not Before	Not After	Common Name	Matching Identities	Issuer Name
2018-07-06T05:53:55.339	2018-05-24T00:00:00	2020-05-23T12:00:00	emailservice.ws.symantec.com	emailservice.ws.symantec.com	C=US, O=DigiCert Inc, OU=www.digicert.com, CN=DigiCert SHA2 Extended Validation Server CA
2018-05-24T23:12:36.567	2018-05-24T00:00:00	2020-05-23T12:00:00	emailservice.ws.symantec.com	emailservice.ws.symantec.com	C=US, O=DigiCert Inc, OU=www.digicert.com, CN=DigiCert SHA2 Extended Validation Server CA
2018-01-19T01:43:14.116	2017-08-02T00:00:00	2018-08-02T23:59:59	emailservice.ws.symantec.com	emailservice.ws.symantec.com	C=US, O=Symantec Corporation, OU=Symantec Trust Network, CN=Symantec Class 3 Secure Server CA - G4
2017-08-02T17:40:40.441	2017-08-02T00:00:00	2018-08-02T23:59:59	emailservice.ws.symantec.com	emailservice.ws.symantec.com	C=US, O=Symantec Corporation, OU=Symantec Trust Network, CN=Symantec Class 3 Secure Server CA - G4