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

Results formailx.utility.app

Logged At	Not Before	Not After	Common Name	Matching Identities	Issuer Name
2024-04-25T03:00:25.87	2024-04-25T02:00:25	2024-07-24T02:00:24	mailx.utility.app	mailx.utility.app	C=US, O=Let's Encrypt, CN=R3
2024-04-25T03:00:25.705	2024-04-25T02:00:24	2024-07-24T02:00:23	mailx.utility.app	mailx.utility.app	C=US, O=Let's Encrypt, CN=R3
2024-04-25T03:00:25.687	2024-04-25T02:00:24	2024-07-24T02:00:23	mailx.utility.app	mailx.utility.app	C=US, O=Let's Encrypt, CN=R3
2024-04-25T03:00:25.66	2024-04-25T02:00:25	2024-07-24T02:00:24	mailx.utility.app	mailx.utility.app	C=US, O=Let's Encrypt, CN=R3
2024-04-25T03:00:25.46	2024-04-25T02:00:23	2024-07-24T02:00:22	mailx.utility.app	mailx.utility.app	C=US, O=Let's Encrypt, CN=R3
2024-04-25T03:00:25.242	2024-04-25T02:00:24	2024-07-24T02:00:23	mailx.utility.app	mailx.utility.app	C=US, O=Let's Encrypt, CN=R3
2024-04-25T03:00:25.103	2024-04-25T02:00:24	2024-07-24T02:00:23	mailx.utility.app	mailx.utility.app	C=US, O=Let's Encrypt, CN=R3
2024-04-25T03:00:23.851	2024-04-25T02:00:23	2024-07-24T02:00:22	mailx.utility.app	mailx.utility.app	C=US, O=Let's Encrypt, CN=R3