Pilo Mail: Self-Hosted Mail with a Relay Gateway
Mailu on one VPS for 20+ domains, plus an authenticated SMTP relay gateway that lets applications send through Brevo or direct, without ever seeing the provider.
Mail looks like a solved problem until you run it. A fresh VPS IP has no sending reputation. Port 25 decides whether the server can receive at all. One missing DNS record turns legitimate mail into spam. And the applications that need to send notifications should never hold a provider API key.
Pilo Mail is the platform built for that reality: Mailu 2024.06 in Docker on a single Contabo VPS, configured for many domains, plus a relay gateway that isolates application sending from the mail server.
The Problem
Three requirements collided. Client mailboxes needed standard IMAP, SMTP, spam filtering, and TLS. Application mail needed a stable, authenticated path that a developer could adopt in minutes. And the provider account needed protection: one leaked key or one shared daily cap can stop every domain at once.
A default Mailu install solves the first requirement and none of the others.
The Approach
Mailu provides Postfix, Dovecot, Rspamd, and the admin surface in eight services. Inbound mail arrives directly on port 25. Submission is 465 with implicit TLS. Outbound goes through Brevo as a smarthost for reputation, with SPF, DKIM, DMARC, MTA-STS, and rDNS configured per domain.
The relay gateway is a separate authenticated submission service on smtp.iterwire.com:2525. Each integration gets four values: host, port, username, password, plus a sender allow-list. Unmapped senders are rejected, never silently rewritten. The application never sees a provider hostname, key, or IP. Adding or changing a provider is a proxy-side change.
Both lanes are live: direct through Mailu and relay through the gateway. The first external client domain runs both.
The Outcome
Live for two owner domains, iterwire.com and logicbison.com, plus the first client domain. The platform is designed for 20+ domains and 50 to 200 mailboxes. Port 25 was verified with a TLS 1.3 handshake, the backup and restore drill passed, and the gateway and direct lanes are both in production.
The operational surface is intentionally boring: a control panel, a health check, a queue view, and a backup script that validates before it overwrites.
Open Pilo Mail
Live mail host. The admin UI requires an operator account; client mailboxes use standard IMAP and SMTP.
Key Takeaway
Mail is a reputation system disguised as a protocol. The code is the easy part; the DNS, the port, and the provider cap decide whether the message arrives.
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