Deliverability

Every update we have filed under Deliverability. 3 entries and counting - newest first.

2026

29SEP 26

Validity Launches "Heatwave", a Blocklist Targeting Artificial Domain Warmup

On 3 September 2026 Validity launched Heatwave, a blocklist that targets synthetic (artificial) domain warming - services that spin up networks of fake mailboxes to fake opens, clicks and replies and manufacture sender reputation. It launched with 1M+ domains listed, is mirrored into Validity's DNS reputation zones, and is used or evaluated by Comcast, Proofpoint, Spamhaus and SURBL - so a listing can affect real delivery. Delisting is a manual review and stopping the warmup is not, on its own, grounds for removal.

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blocklistwarmupcold-emailvalidity

28SEP 26

DeliverabilityLow impact

AI Assistants Can Now Run Live Email-Deliverability Checks (via MCP)

AI assistants like Claude can now run real email-deliverability checks through MCP (the Model Context Protocol), an open standard for connecting tools to assistants. Anthropic's Connectors Directory now lists such tools, so a user can ask "is my domain blacklisted?" and the assistant runs the actual check on the tool's infrastructure rather than guessing from training data. Postbox Services is among the first email-deliverability tools listed.

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mcpai-assistantstooling

9AUG 26

DeliverabilityMedium impact

APRF: The Draft Standard That Would Finally Show Senders Where Their Mail Lands

A new IETF draft (draft-brotman-aggregate-performance-reporting) proposes a DMARC-style mechanism for mailbox providers to email senders daily JSON reports on inbox placement and engagement - keyed to the DKIM signing domain, not the From address. It is early (Comcast is the only provider sending beta reports, with a Google engineer among the authors), but it could finally standardize the placement data that has always lived behind per-provider portals.

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aprfietf-draftreporting