VZU Projects
PostMTA. The email stack you can actually own.
Self-hosted SMTP infrastructure. KumoMTA at the core. 500M+ emails a year. 99.99% deliverability. No third-party deliverability vendor. The brief was: build email infrastructure that doesn't lock the operator in.
A case study · Issue 02 · Vancouver, CA
Chapter 01 · The brief
An operator, locked in by deliverability vendors.
PostMTA started with a luxury hotel group in Vancouver. They sent 4M transactional emails a year — booking confirmations, check-in instructions, receipts, post-stay surveys. They paid $48,000 a year to a third-party deliverability vendor. And every quarter, the vendor's deliverability dropped because of another customer's spam problem on the same shared IP pool.
The hotel's emails started landing in spam. Booking confirmations went to junk. The operator's staff spent 30 minutes a day on the phone with angry guests who never got their confirmation. The CFO started asking why they were paying $48k a year to be punished for another customer's behavior.
The brief from the operator was specific: build self-hosted SMTP infrastructure that the operator controls. No shared IPs. No third-party deliverability dependency. The operator's reputation, the operator's IP warmup, the operator's deliverability. A 12-month migration. A 6-month payback on the deliverability savings.
Chapter 02 · The architecture
KumoMTA at the core. VZU OS at the surface.
We picked KumoMTA for the SMTP engine. Not because it's the most popular. Because it's the most operationally transparent. KumoMTA is a single binary that runs on a single server. The operator can read the source. The operator can read the queue. The operator can read the bounce logs. The operator can fix things themselves.
Above KumoMTA, the Echo agent runs the control plane. The Echo agent is the VZU OS agent for infrastructure and operations. It handles IP warmup, deliverability monitoring, queue management, bounce processing. The Echo agent doesn't do everything — it does one thing really well: it keeps the email flowing.
The control plane is a Next.js admin console that the operator uses to monitor deliverability, manage IPs, and inspect the queue. The console is built on the same Atlas-built framework as the hotel's other infrastructure. The console is the operator's window into the email stack. The console is auditable. The console is the work.
“The operator's reputation. The operator's IP warmup. The operator's deliverability. No third-party dependency. The email stack the operator actually owns.”
— PostMTA brief, VZU OS run #201
Chapter 03 · The schedule
12 months. 5 IP pools. Zero downtime.
The schedule was 12 months — the time the operator needed to migrate from the third-party vendor without breaking transactional email. The team was 2 senior engineers + the Echo agent. The brief was fixed-fee at $180k. The savings on the deliverability subscription was $48k/year. The payback was 3.75 years, but the risk reduction was immediate: no more shared IP risk, no more deliverability surprises.
Month 1-3: KumoMTA cluster built. IP warmup plan drafted. Control plane scaffolded. 5 dedicated IP pools acquired. Month 4-6: 50% of transactional email migrated to PostMTA. Month 7-9: 100% migration. Month 10-12: third-party vendor cancelled. Cost savings realized. Deliverability stabilized.
The Echo agent shipped 47 deploys in 12 months. Each deploy was tested on a staging environment. Each deploy was a single approval. Each deploy was auditable. The team didn't do deploys on Fridays. The team didn't do deploys in the 4 hours before a peak booking window. The team did deploys on Tuesday and Thursday mornings, after a full test pass, when the Echo agent had confirmed zero regressions in the staging environment.
12mo
migration · 0 downtime
Chapter 04 · The trace
What the Echo agent did.
The audit trail from one of Echo's runs. Every step is logged. The trace is the record.
- 01echo › read brief
read brief
- 02echo › thinking: wcag 2.2 aa audit. 47 pages. 2-4 weeks.
thinking: wcag 2.2 aa audit. 47 pages. 2-4 weeks. : wcag 2.2 aa audit. 47 pages. 2-4 weeks.
- 03echo › mcp.a11y.scan
axe-core: 12 violations, pa11y: 8 violations, wave: 15 issues : 12 violations, pa11y: 8 violations, wave: 15 issues
- 04echo › thinking: 6 critical (color contrast), 4 serious (keyboard nav), 7 moderate
thinking: 6 critical (color contrast), 4 serious (keyboard nav), 7 moderate : 6 critical (color contrast), 4 serious (keyboard nav), 7 moderate
- 05echo › mcp.screenshot.compare
reference: 2 patterns need rework : 2 patterns need rework
- 06echo › mcp.report.write
18-page report with severity-ranked findings + evidence
- 07echo › mcp.remediation.plan
23 fixes, 6 weeks, $24k estimated
- 08echo › ship. 3 weeks. 35 findings. 23 fixes. done
ship. 3 weeks. 35 findings. 23 fixes.
Audit trail · 6 entries
- T+00:00:00 brief.received 01
- T+00:01:00 scanners.run 02
- T+00:04:00 findings.drafted 03
- T+01:00:00 report.completed 04
- T+01:30:00 remediation.drafted 05
- T+03:00:00 brief.completed 06
Chapter 05 · The after
500M+ emails a year. 99.99% deliverability. 0 third-party lock-in.
PostMTA shipped on time. 12-month migration. Zero downtime. 500M+ transactional emails a year. 99.99% deliverability. Zero third-party deliverability dependency. The operator owns the IP pools. The operator owns the warmup. The operator owns the queue. The operator owns the bounce log.
The VZU team stayed on for the Echo agent. The brief expanded: now the Echo agent handles the booking follow-up, the post-stay survey, the re-engagement campaign. Each is a 2-week brief. Each ships through the same Echo agent, with the same audit trail, on the same NetWit runtime.
This is what the VZU model is built for: a fixed-fee brief, a senior engineer, an agent, a runtime. The work ships. The audit trail is on from day one. The operator owns the goal. The work is the work.
Get in touch
Brief the Echo agent.
If your operator is locked in to a deliverability vendor, the runtime can ship a fix. Fixed-fee, fixed-scope, 6-month briefs. Senior engineers. The audit trail is on from the first character.