Transmit vs Brevo: Focused Email Infrastructure vs. All-in-One Everything

The problem with trying to do everything

Brevo (formerly Sendinblue) has expanded from an email tool into an all-in-one platform: email, SMS, WhatsApp, live chat, meetings, CRM, landing pages, and ads. That scope is the product pitch and the product problem.

When a platform spreads engineering effort across seven product categories, email stops being the focus. You see this in Brevo's dashboard, which surfaces CRM contacts, deal pipelines, and chat widgets alongside your sending configuration. For a small business owner who wants one login for everything, that may be useful. For a developer who needs reliable transactional email with predictable deliverability and clean API semantics, the extra surface area is friction.

Transmit does one thing: send email well. Clean API, automated warmup, reputation isolation per organization, and a BYOK mode if you want to keep data in your own AWS account.

Deliverability on shared infrastructure

Brevo's free and lower-paid tiers use shared IP pools. Your sending reputation is influenced by every other sender on the same IP ranges. If Brevo's shared IPs have a history of spam complaints from other users, your legitimate emails arrive in junk folders. Brevo does offer dedicated IPs, but they are available only on higher plans and require a manual warmup process you manage yourself.

Transmit handles this differently depending on which mode you choose.

Managed mode provides reputation isolation at the organization level. Each organization's sending reputation is tracked independently. Your complaints and bounces do not contaminate other customers on the platform, and theirs do not contaminate yours.

BYOK mode connects to your own AWS SES account. Your sending reputation lives entirely in your own AWS infrastructure. Transmit's warmup scheduler ramps your domain volume automatically and pauses on bounce spikes. You own the deliverability outcome.

Neither mode puts your email on a shared IP pool with unknown senders.

What the API actually looks like

Brevo has a REST API, but it is shaped around their full platform. API calls reference Brevo-specific concepts like "contacts," "lists," and "campaign templates" that are tied to their proprietary data model. Migrating away from Brevo means rewriting those integrations.

Transmit's API is straightforward:

curl -X POST https://api.xmit.sh/email/send \
  -H "Authorization: Bearer pm_live_xxxxx" \
  -H "Content-Type: application/json" \
  -d '{
    "to": "user@example.com",
    "from": "hello@yourapp.com",
    "subject": "Your order shipped",
    "html": "<p>Your order #1234 is on its way.</p>"
  }'

Full reference: /docs/send-email

You can also send via SMTP if you are integrating with a framework that prefers SMTP transport over HTTP. Same credentials, same deliverability infrastructure, different wire protocol.

Feature comparison

Automated warmup: a feature Brevo skips

If you add a new sending domain on Brevo, you get a checklist of DNS records to add and then you are on your own for warmup. Brevo's documentation recommends starting with low volumes and gradually increasing over weeks. How you track that, how you pause when things go wrong, and how you know when you are done is left to you.

Transmit's warmup scheduler handles this automatically. It ramps your daily sending volume on a configurable curve, monitors bounce and complaint rates in real time, and pauses sending if rates cross thresholds. You get a dashboard view of where each domain sits in the warmup curve. When warmup completes, you move to full sending capacity without touching anything.

This is especially relevant if you are managing multiple sending domains or if you are launching a new product and cannot afford to burn your domain reputation in the first week.

Sequences and inbound routing

Brevo has a visual automation builder for drip campaigns. Transmit has sequences that are fully API-driven. You enroll contacts programmatically, define step delays in the API payload (minutes, hours, or days), and the scheduler handles delivery timing. No GUI dependency for enrollment or step progression.

Inbound email routing is not something Brevo supports at all. If you need to receive replies to transactional emails, parse them, route them to a webhook, or forward them to another address, Transmit handles that natively. Brevo has no inbound path.

When Brevo still makes sense

Brevo is a reasonable fit for small businesses that genuinely need the bundled CRM, email, and SMS stack and want one vendor invoice. The price-per-email on their paid tiers is competitive and the drag-and-drop campaign builder is accessible to non-technical users.

If your primary requirement is developer-facing email infrastructure with clean API semantics, automated warmup, and no shared IP exposure, Brevo is the wrong shape for that job.

Getting started with Transmit

The free BYOK tier needs no credit card. Connect your AWS account via a one-click CloudFormation template, verify your domain, and send your first email in minutes. BYOK setup guide here.

Managed mode skips the AWS setup entirely. Start at $2/month, no infrastructure to manage.