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

Results formail.alignedservice.com

Logged At	Not Before	Not After	Common Name	Matching Identities	Issuer Name
2018-04-24T19:32:42.285	2018-04-24T00:00:00	2018-07-23T23:59:59	alignedservice.com	mail.alignedservice.com	C=US, ST=TX, L=Houston, O="cPanel, Inc.", CN="cPanel, Inc. Certification Authority"
2018-04-24T19:32:15.909	2018-04-24T00:00:00	2018-07-23T23:59:59	alignedservice.com	mail.alignedservice.com	C=US, ST=TX, L=Houston, O="cPanel, Inc.", CN="cPanel, Inc. Certification Authority"
2017-08-26T17:59:01.509	2017-08-24T00:00:00	2017-11-22T23:59:59	alignedservice.com	mail.alignedservice.com	C=US, ST=TX, L=Houston, O="cPanel, Inc.", CN="cPanel, Inc. Certification Authority"
2017-06-03T17:47:46.941	2017-05-30T00:00:00	2017-08-28T23:59:59	alignedservice.com	mail.alignedservice.com	C=US, ST=TX, L=Houston, O="cPanel, Inc.", CN="cPanel, Inc. Certification Authority"