OB-003 is BounceNot, an email verification service. It is the second record that checks things about the people on the other side of a form, and it shares an engine with the first.
The observation
Every team that sends email eventually cleans a list. Most do it rarely: before a campaign, after an import, when the bounce rate starts to hurt. The services that do it for them mostly want a subscription, which is the wrong shape for a job that happens twice a year.
The decision
Price it per address and nothing else. One credit verifies one address and costs one cent; buy any amount from $5 to $1,000, keep the credits until you use them, and start with 100 for free. The first commit was on 12 July 2025, and the product around that decision is a list you can upload in a minute, results you can filter and export, and an API for the teams that would rather check at sign-up than clean afterwards.
The checking itself runs through ip-api, OB-001. Two products share one email validation engine, which means one place to keep it correct.
The working result
In October 2026 BounceNot was rewritten from Kotlin and PostgreSQL to Rust and SQLite, with identical routes, JSON and pages, and moved from bouncenot.com to bouncenot.oddbench.co. The whole service is one binary of about 13 MB that uses about 25 MB of memory.
The rewrite also changed one answer. When a mail server replies to a check with a temporary refusal, it means “not now” and says nothing about whether the mailbox exists. The old version read too much into that; the new one reports the address as unknown, and unknown is never turned into invalid, so a working address is never deleted on a guess. It is a less decisive answer and a more correct one.