Integrations Updated 3 minutes ago 3 min read

Connecting Mailjet or any other email provider not in the marketplace

Mailjet isn't a one-click integration yet, but you can still use it — here's the honest how, and why raw SMTP isn't an option.

Every OverSkill app can already send email out of the box — no setup required. See Sending emails from your app for that. But if you specifically want to use Mailjet (or another email provider like Postmark, Mandrill, or Brevo that isn't in our integrations marketplace yet), here's the honest answer: it's not a one-click connection today, but you can still wire it up.

Two different questions, two different answers

People asking about Mailjet are usually really asking one of two things:

Can I use Mailjet's API to send email? — Yes. Keep reading.

Can I connect via raw SMTP (the mail-server protocol, port 25/465/587)? — No. OverSkill apps run on a serverless platform that doesn't support opening raw SMTP connections. This isn't a Mailjet-specific limitation or something wrong with your setup — no app built on OverSkill can speak SMTP directly, to any provider.

Using Mailjet via its API

Mailjet offers an HTTP API for sending email, and that works fine here. Two steps:

  1. Add your Mailjet credentials as environment variables. In your app's Settings → Environment Variables, add MAILJET_API_KEY and MAILJET_API_SECRET, marking both as secret. Never paste API keys into chat — the Environment Variables panel keeps them server-side only.
  2. Ask the AI to build the send logic. For example:

Create an endpoint that sends email through Mailjet's API using my MAILJET_API_KEY and MAILJET_API_SECRET, and call it when someone signs up.

The AI creates a proper server-side endpoint that calls Mailjet's Send API — your keys stay private, never exposed to the browser.

This same pattern works for any email provider with an HTTP API, not just Mailjet — Postmark, Mandrill, Brevo (formerly Sendinblue), SMTP2Go, and others all work the same way even before they show up as a featured integration in our marketplace.

When to use this vs. the built-in sender vs. Resend/SendGrid

  • Don't care which provider, just want email working now? Use the built-in shared sender — nothing to connect.
  • Want to send from your own domain today (like [email protected])? Connect Resend or SendGrid — see Sending email from your own custom domain. Those two are pre-built one-click integrations right now.
  • Specifically need Mailjet (existing account, existing templates, existing deliverability reputation)? Use the API pattern above.

Why not SMTP?

Worth understanding once so it doesn't come up again: your app's backend runs on a modern serverless platform, not a traditional server with unrestricted networking. That platform is built for fast HTTP requests, not for holding open raw socket connections to arbitrary mail servers. Every major provider (Mailjet included) offers an HTTP API precisely so apps like yours don't need SMTP — so you're not missing anything by using the API instead.

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