Company email on a custom domain, built twice

Once as a mail server I look after, once as a serverless pipeline.

RoleSole engineer

ScopeDesign, build, run

Built inAbout six weeks

Still runningYes, both

Jobxy and Sumber Holistik, my dad’s agency, both needed staff email on their own domains. In the summer of 2026 I built Jobxy’s as a mail server that I administer, and Sumber Holistik’s as a serverless pipeline. Both are in use today, which is also why I cannot share the code or the configuration.

Two builds

The server I run

Jobxy’s mail. A hosted stack that I administer end to end.

Postfix for transport, Dovecot for mailboxes

TLS everywhere, fail2ban at the edges

Nightly backups with a restore I have tested

Predictable cost, but I am the one who fixes it when it breaks

The serverless pipeline

Sumber Holistik’s mail. Inbound and outbound mail through managed functions and an email API. There is no server to patch.

Functions handle receipt, parsing and routing

Objects in cheap storage instead of a mail spool

Near-zero cost at rest, scales on send

Less control, far less maintenance

How a message is handled

01Composethe app or client hands off a message

02AuthenticateSPF, DKIM signing, DMARC alignment

03Routeserver queue, or a function handler

04Deliverretries and bounce handling

05Storemailbox or object storage, backed up

What went wrong

Early sends passed every test I had written and still landed in spam. The fix was in DNS: SPF, DKIM, and a DMARC policy that starts at none, gets read for two weeks, then tightens. I now check deliverability regularly, and the reverse-DNS and warm-up notes are written down in a runbook.

Results

Staff addresses live on the company domain, with no per-seat suite licence.

DMARC reports get read, so I can see when deliverability drops.

A written runbook, so recovery does not depend on me being reachable.