Blog

Notes from the team. Engineering deep-dives, product changes, and the occasional war story.

• 2026-04-15

  Why we rewrote our mail engine in a weekend

  Stalwart kept silently overriding our config from the DB. We replaced it with Postfix + a tiny Node SMTP shim and shipped. Here's the story.

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• 2026-05-04

  MCP is the new SDK: shipping @jassra25/inboxr-mcp on day one

  We built the MCP server before the REST docs were polished. Here's why agent-first beats agent-also, and what 16 tools look like when you start from "an LLM should drive this end-to-end."

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• 2026-05-01

  How to ship SMS without a carrier deal

  Most disposable SMS services need a Twilio relationship and 30-day approvals. We use a fleet of physical Pixels on prepaid SIMs, route inbound via a 30-minute claim window, and bill PAYG. Here's the architecture.

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• 2026-04-28

  Webhooks that don't lie: what we changed after a 4am incident

  A receiver returned 200 with an HTML error page. We marked it delivered. Two days of silent data loss. The fix: capture response body on every attempt — success or failure — and surface it in the dashboard.

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• 2026-04-22

  Rate limiting without Redis: a 30-line Postgres helper

  Adding Redis just for rate limits felt like a tax. A single ON CONFLICT … DO UPDATE upsert against a (scope, key, window_start) row gets you 5/sec/tenant + 60/min/phone with no new infra.

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• 2026-04-18

  Pricing on two axes: email and SMS bill independently

  Most platforms force you onto one ladder. We split email and SMS into two independent plans because the cost shapes differ — email is mostly storage, SMS is mostly per-message. The pricing page is honest about that.

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