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Sender Score vs Microsoft SNDS: catalog facts
Sender Score	Microsoft SNDS
Free The score lookup and related tools are offered free by Validity.	Free Free for senders who register their networks.
Web	Web
Quick reputation score for an IP address or domain Return Path Blocklist lookup and removal request in one place	Reputation data directly from Outlook.com Junk email feedback loop in the same portal
Site also promotes Validity's paid email services Score reflects Validity's own data rather than every mailbox provider	Requires login and verified control of the IP ranges Access expires and must be reattested periodically
Web application	Hosted service
Closed source	Closed source
License not stated	License not stated
Not stated if an account is needed	Account needed
Needs internet	Needs internet
Official website Full listing and sources Checked September 24, 2026	Official website Full listing and sources Checked September 24, 2026

Catalog facts only. Anything “not stated” is unconfirmed. Check full listings for details.