How to Connect useSend to Mailbase

Overview

There are two ways to send with Mailbase, and the first decision is which one you're doing. Hosted Mailbase sending is the no-infrastructure path: verify a sender domain and you're sending on managed infrastructure. Bring-your-own (BYO) useSend is for teams that already run — or want to run — their own useSend instance and keep delivery on infrastructure they control, paying €5/mo for the Mailbase workflow layer on top. This guide covers the BYO connection step by step, and when to pick each.

Before you connect (BYO useSend)

For the BYO path you need a running useSend instance and four credentials to hand Mailbase. Get useSend deployed first — on Docker, Coolify, or Railway — with its domain configured and Amazon SES connected for delivery. If you're choosing managed sending instead, skip all of this: just verify a sender domain in Mailbase and you're done.

Have these ready from your useSend instance: the API URL, an API key, your default from address, and a webhook secret. Authenticate the sending domain (SPF/DKIM/DMARC) before you start sending real volume.

• A running useSend instance (Docker/Coolify/Railway) on SES
• useSend API URL + API key
• Default from address + webhook secret
• Sending domain authenticated (SPF/DKIM/DMARC)

Connecting useSend to Mailbase, step by step

The connection itself is quick once useSend is ready:

• Record your domain, sending region, and API-key scope
• Verify the webhook delivers events before sending volume
• Keep bounce/complaint handling wired so suppression works

1. Choose your mode: hosted Mailbase sending (verify a sender domain and stop here) or BYO useSend (continue).
2. In Mailbase settings, open the useSend connection.
3. Paste your useSend API URL, API key, default from address, and webhook secret.
4. Test the connection so Mailbase confirms it can reach useSend and read status.
5. Confirm the webhook is receiving delivery, bounce, and complaint events so suppression and analytics work.
6. Start working: compose MJML campaigns, run A/B tests, use the shared reply inbox and AI drafts — all routing through your useSend delivery.

Hosted vs BYO: which to choose

Choose hosted Mailbase sending if you want the workflow without operating any infrastructure — fastest to start, nothing to deploy. Choose BYO useSend if you already run useSend (or want to), need delivery on your own infrastructure for cost or control reasons, and are comfortable owning deliverability. Both give you the same Mailbase workflow layer — reply inbox, campaigns, AI, analytics — on top.

You're not locked in either way: the connection model means you can run your own useSend now and the workflow stays the same if your setup changes. See the useSend integration page for the BYO plan details.

• Hosted: no infrastructure, verify a domain, start sending
• BYO useSend: delivery on your infra, €5/mo for the workflow layer
• Same workflow layer on top either way

Common mistakes

• Choosing a tool before deciding who owns deliverability.
• Treating DNS authentication as a one-time checkbox instead of an operating baseline.
• Mixing product-critical transactional email with experimental marketing sends, with no clear boundary.
• Trusting headline metrics (like open rate) that privacy proxies now inflate.

Sources and further reading

Official docs for current setup details, pricing, and API behavior — verify specifics there, since they change.

Related guides

More on connect usesend to mailbase and the surrounding usesend workflow: