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

Results forwebmail.policytm.com

Logged At	Not Before	Not After	Common Name	Matching Identities	Issuer Name
2018-09-08T23:06:51.046	2018-09-08T00:00:00	2018-12-07T23:59:59	policytm.com	webmail.policytm.com	C=US, ST=TX, L=Houston, O="cPanel, Inc.", CN="cPanel, Inc. Certification Authority"
2018-09-08T23:06:32.285	2018-09-08T00:00:00	2018-12-07T23:59:59	policytm.com	webmail.policytm.com	C=US, ST=TX, L=Houston, O="cPanel, Inc.", CN="cPanel, Inc. Certification Authority"
2018-08-07T17:10:03.28	2018-08-07T00:00:00	2018-11-05T23:59:59	policytm.brillianttricks.com	webmail.policytm.com	C=US, ST=TX, L=Houston, O="cPanel, Inc.", CN="cPanel, Inc. Certification Authority"
2018-08-07T17:09:45.694	2018-08-07T00:00:00	2018-11-05T23:59:59	policytm.brillianttricks.com	webmail.policytm.com	C=US, ST=TX, L=Houston, O="cPanel, Inc.", CN="cPanel, Inc. Certification Authority"