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

Results forwebmail.mrm.hdwebdev.com

Logged At	Not Before	Not After	Common Name	Matching Identities	Issuer Name
2020-02-27T01:29:53.441	2020-02-27T00:00:00	2020-05-27T23:59:59	mrm.hdwebdev.com	webmail.mrm.hdwebdev.com	C=US, ST=TX, L=Houston, O="cPanel, Inc.", CN="cPanel, Inc. Certification Authority"
2020-02-27T01:29:23.68	2020-02-27T00:00:00	2020-05-27T23:59:59	mrm.hdwebdev.com	webmail.mrm.hdwebdev.com	C=US, ST=TX, L=Houston, O="cPanel, Inc.", CN="cPanel, Inc. Certification Authority"
2020-01-28T11:20:52.829	2020-01-28T00:00:00	2020-04-27T23:59:59	mrm.hdwebdev.com	webmail.mrm.hdwebdev.com	C=US, ST=TX, L=Houston, O="cPanel, Inc.", CN="cPanel, Inc. Certification Authority"
2020-01-28T11:20:38.284	2020-01-28T00:00:00	2020-04-27T23:59:59	mrm.hdwebdev.com	webmail.mrm.hdwebdev.com	C=US, ST=TX, L=Houston, O="cPanel, Inc.", CN="cPanel, Inc. Certification Authority"