Senior Email Infrastructure Engineer

OpenMail is email infrastructure for a new class of internet user: AI agents. Every agent gets a real inbox. It can sign up for a tool, receive a verification code, reply to a customer, no human in the loop.

Agents have no way to prove who they are online. Email already does that for every account on the internet, so it becomes the identity for agents too.

We believe agents on the internet will outnumber humans. The infrastructure for that doesn't exist. We're building it.

The role

Today we run on a third-party email infrastructure provider. Tomorrow, you move us onto infrastructure we own, and you design it from scratch, technology choices included.

Scope: inbound MX pipeline, per-customer DKIM signing, outbound queue, bounce handling, feedback loops, IP warming, blocklist monitoring, and abuse controls across all of it.

You'll build in Node.js and TypeScript: Fastify, Prisma, Postgres, BullMQ.

The hard problems

• Outrun the blocklists. The world scores senders by IP and domain. We run thousands of agents per customer behind them. One goes bad, everyone gets punished. You'll have to catch it before the world does, every time. 

• Bootstrap trust from nothing. A fresh agent has no history. Per-agent trust gets farmed through disposable identities. Customer-inherited trust is a model nobody has built cleanly. You'll have to design one that works.

• Make machine traffic deliverable. Providers score senders on human fingerprints: timing, variance, replies. Agentic mail fails those checks by nature. Build sending behavior, warming, and feedback signals that earn inbox placement for traffic no filter was designed to trust.

If reading this list made you want to start sketching solutions, you're who we're looking for.

Who you are

• You've built and run mail systems in production, whether your own MTA (Haraka, Postfix, Exim) or a real platform on top of a provider (SES, Mailgun, Postmark, Halon, Mailchannels).

• You've owned a system end to end and carry the scars to prove it. Outbound deliverability battles, blocklist delisting, ISP relations: strong plus.

• You hold technical opinions and defend them when challenged.

• You know which layers to own and which to rent.

• When something's broken or missing, you fix it before anyone asks.

Who you'd work with

Two co-founders, split by domain. Jokūbas owns GTM and commercial. Armandas owns product and infrastructure today. Tomorrow, infrastructure becomes yours, and you'd work with him day to day.

What we care about

Technical excellence, real debate, craft, extreme ownership, speed. We built this to real revenue nights and weekends before a euro of funding existed. That pace doesn't change.

What this is

A startup. Some weeks are intense. Priorities shift when we learn something. There's no platform team behind you. You are the platform team.

In exchange: your decisions ship the same week, your equity means something, nobody sits between you and the outcome. We think that's the fun part.

Details

Vilnius-based, or open to relocating.

Compensation: €5K to €9K gross per month, depending on seniority, plus 1 to 3% equity. For the right person, the conversation goes beyond that, up to co-founder level.

If this is your kind of problem, apply.