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

Results foremail.send.webffinity.com

Logged At	Not Before	Not After	Common Name	Matching Identities	Issuer Name
2025-12-06T13:12:24.259	2025-12-06T12:13:54	2026-03-06T12:13:53	email.send.webffinity.com	email.send.webffinity.com	C=US, O=Let's Encrypt, CN=E7
2025-12-06T13:12:24.108	2025-12-06T12:13:54	2026-03-06T12:13:53	email.send.webffinity.com	email.send.webffinity.com	C=US, O=Let's Encrypt, CN=E7
2025-10-07T14:10:51.586	2025-10-07T13:12:21	2026-01-05T13:12:20	email.send.webffinity.com	email.send.webffinity.com	C=US, O=Let's Encrypt, CN=E8
2025-10-07T14:10:51.407	2025-10-07T13:12:21	2026-01-05T13:12:20	email.send.webffinity.com	email.send.webffinity.com	C=US, O=Let's Encrypt, CN=E8
2025-08-08T15:09:16.7	2025-08-08T14:10:46	2025-11-06T14:10:45	email.send.webffinity.com	email.send.webffinity.com	C=US, O=Let's Encrypt, CN=E5
2025-08-08T15:09:16.487	2025-08-08T14:10:46	2025-11-06T14:10:45	email.send.webffinity.com	email.send.webffinity.com	C=US, O=Let's Encrypt, CN=E5