Notes from the team

Deliverability, infrastructure, and the unsexy details of running an email service. Subscribe via RSS.

2026-05-08 Engineering · 8 min read

Why we run our own MTAs

Most "email APIs" are a thin wrapper around someone else's deliverability problem. This post explains why we made the heavier choice to run our own outbound MTAs — Haraka, on dedicated bare metal — and what we get from it that an API wrapper can't deliver.

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2026-05-07 Postmortem · 6 min read

The 8 MB inbound bug we just fixed

Cloudflare Analytics showed three errors against our /v1/inbound endpoint. Three errors a day, every day. We finally chased it down: an 8 MB request-body cap that real Gmail forwards routinely exceed. A short postmortem on the diagnosis, the fix, and the defensive layer we added to catch this class of bug earlier.

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2026-05-04 Deliverability · 9 min read

Multi-region deliverability — why one region isn't enough

The first question potential customers ask after pricing: "do you have an EU region?" The second: "why does it matter if I'm sending from the US anyway?" This is the long answer — covering DMARC alignment, MTA-STS, recipient-server geographic latency, and the GDPR ground truth.

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