Outlook.com SNDS IP Data and IP Status reports via the OAuth-secured REST API.
Free
2 servers across email. The largest is Outlook SNDS.
Outlook.com SNDS IP Data and IP Status reports via the OAuth-secured REST API.
Gmail Postmaster Tools v2 — domains, traffic metrics, and compliance via your own Google OAuth.
The rest either hold an API key issued by the publisher or ask for nothing.
Listed without a verification tick. Read the listing before installing.