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Tool · 06

Multiple ESP Mailer

A high-throughput sending engine that dispatches your campaigns across multiple email service providers at once — with per-provider rate limits, retries, and suppression built in.

One queue, every ESP.

Overview

The Multiple ESP Mailer is the sending core of our stack. Instead of tying your program to one provider, it spreads volume across every ESP you connect — balancing load, respecting each provider's limits, and recording every attempt so nothing slips through the cracks.

Why teams use it
  • Send at scale without babysitting individual providers
  • Protect deliverability with automatic rate control
  • Never lose a send — every attempt is recorded
Features

What it does.

01

Multi-ESP rotation

Send through AWS SES, Brevo, Mailtrap, self-hosted Mailcow and more from one pipeline.

02

Per-provider rate limiting

Set global or per-ESP send rates so you stay within each provider's limits automatically.

03

Queue & retry engine

A fast, Redis-backed queue with automatic retries on transient failures and duplicate suppression.

04

Full send tracking

Every attempt is logged — queued, sending, sent, failed, or suppressed — for complete auditability.

05

Horizontal scaling

Shard sending across multiple servers, each claiming its own slice of the queue.

06

Suppression & compliance

Suppression lists and unsubscribe handling enforced before any message leaves the queue.

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