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

Results forwebmail.saacdevelopers.tech

Logged At	Not Before	Not After	Common Name	Matching Identities	Issuer Name
2021-02-19T15:34:24.433	2021-02-19T14:34:24	2021-05-20T14:34:24	webmail.saacdevelopers.tech	webmail.saacdevelopers.tech	C=US, O=Let's Encrypt, CN=R3
2021-02-19T15:34:24.335	2021-02-19T14:34:24	2021-05-20T14:34:24	webmail.saacdevelopers.tech	webmail.saacdevelopers.tech	C=US, O=Let's Encrypt, CN=R3
2020-03-15T18:53:53.523	2020-03-15T17:53:53	2020-06-13T17:53:53	saacdevelopers.tech	webmail.saacdevelopers.tech	C=US, O=Let's Encrypt, CN=Let's Encrypt Authority X3
2020-03-15T18:53:53.317	2020-03-15T17:53:53	2020-06-13T17:53:53	saacdevelopers.tech	webmail.saacdevelopers.tech	C=US, O=Let's Encrypt, CN=Let's Encrypt Authority X3
2020-03-14T19:01:58	2020-03-14T18:01:57	2020-06-12T18:01:57	saacdevelopers.tech	webmail.saacdevelopers.tech	C=US, O=Let's Encrypt, CN=Let's Encrypt Authority X3
2020-03-14T19:01:57.783	2020-03-14T18:01:57	2020-06-12T18:01:57	saacdevelopers.tech	webmail.saacdevelopers.tech	C=US, O=Let's Encrypt, CN=Let's Encrypt Authority X3