Built-In Email

Diploi provides a lightweight SMTP relay inside every deployment so your applications can send email without provisioning an external provider. The service is intended for development and low-volume operational notifications.
The SMTP relay is included with your deployment at no additional cost.

Connection details

Connect using these values:

Host: core.diploi
Port: 2525
Authentication: Not required

Example configuration

import nodemailer from "nodemailer";

const transporter = nodemailer.createTransport({
  host: "core.diploi",
  port: 2525,
});

await transporter.sendMail({
  to: "user@example.com",
  subject: "Verify your email",
  text: "Click the link in the email to verify your account.",
});

Component integration

The Supabase component automatically points its email authentication workflows at this relay, giving you out-of-the-box email confirmation flows without additional configuration.

Usage limits

Maximum 10 messages per hour
Maximum 30 messages per day
Contact support if you need higher throughput

Header normalization

To protect deliverability, Diploi rewrites certain email headers. These headers are stripped if present:

from
to
sender
reply-to
return-path
resent-from
resent-to
resent-sender
bcc
cc
errors-to
x-original-from
x-envelope-from

Diploi sets the from address to your project’s default domain for every message.

Best practices

Use the relay for development and staging workloads; production-grade email should use a dedicated provider once you outgrow the limits.
Keep transactional content concise to avoid hitting daily limits.
Reach out to support if you need custom limits or additional deliverability controls.