SMTP Relay

Sendry provides an SMTP relay for applications that cannot use the REST API directly. Connect using standard SMTP and authenticate with any Sendry API key that has sending_access scope.

This is ideal for:

• Legacy apps that only support SMTP
• Self-hosted tools like Gitea, n8n, or Directus
• Email clients and mail merge tools

---

Connection details

Fetch your current SMTP connection settings from the API:

GET /v1/smtp/info

Requires any valid API key (read_only or higher).

Response

{
  "host": "smtp.sendry.online",
  "port": 587,
  "tls": false,
  "auth": {
    "username": "(any value)",
    "password": "use any API key with sending_access scope"
  }
}

Settings at a glance

Setting	Value
Host	smtp.sendry.online
Port	587 (STARTTLS)
Security	STARTTLS (upgrade on connect)
Username	Any non-empty string (e.g. sendry)
Password	Your Sendry API key (sn_live_...)

Port 465 (SMTPS/implicit TLS) is not currently supported. Use port 587 with STARTTLS.

---

Configuration examples

Nodemailer (Node.js)

import nodemailer from "nodemailer";

const transporter = nodemailer.createTransport({
  host: "smtp.sendry.online",
  port: 587,
  secure: false, // STARTTLS
  auth: {
    user: "sendry",
    pass: process.env.SENDRY_API_KEY,
  },
});

await transporter.sendMail({
  from: "hello@acme.com",
  to: "user@example.com",
  subject: "Hello from SMTP!",
  html: "<p>Sent via Sendry SMTP relay.</p>",
});

Python (smtplib)

import smtplib
import os
from email.mime.text import MIMEText
from email.mime.multipart import MIMEMultipart

msg = MIMEMultipart("alternative")
msg["From"] = "hello@acme.com"
msg["To"] = "user@example.com"
msg["Subject"] = "Hello from SMTP!"
msg.attach(MIMEText("<p>Sent via Sendry SMTP relay.</p>", "html"))

with smtplib.SMTP("smtp.sendry.online", 587) as smtp:
    smtp.ehlo()
    smtp.starttls()
    smtp.login("sendry", os.environ["SENDRY_API_KEY"])
    smtp.sendmail("hello@acme.com", ["user@example.com"], msg.as_string())

Go

package main

import (
    "net/smtp"
    "os"
)

func main() {
    auth := smtp.PlainAuth(
        "",
        "sendry",
        os.Getenv("SENDRY_API_KEY"),
        "smtp.sendry.online",
    )

    msg := []byte(
        "From: hello@acme.com\r\n" +
        "To: user@example.com\r\n" +
        "Subject: Hello from SMTP!\r\n" +
        "MIME-Version: 1.0\r\n" +
        "Content-Type: text/html\r\n\r\n" +
        "<p>Sent via Sendry SMTP relay.</p>",
    )

    err := smtp.SendMail(
        "smtp.sendry.online:587",
        auth,
        "hello@acme.com",
        []string{"user@example.com"},
        msg,
    )
    if err != nil {
        panic(err)
    }
}

Environment variable approach (12-factor apps)

Most tools that support SMTP will accept a SMTP_URL:

smtp://sendry:sn_live_your_api_key@smtp.sendry.online:587

Set this as an environment variable and reference it in your app config.

---

Domain verification

SMTP sends are subject to the same domain verification requirement as the REST API. The From address must use a domain that is verified in your Sendry account.

To verify a domain: go to Domains in the dashboard, or use the Domains API.

During development, use a test-mode key (sn_test_...) to bypass domain verification.

---

Limitations

Feature	REST API	SMTP relay
Attachments	Yes	Yes
Custom headers	Yes	Yes
Batch sending	Yes	No
Templates	Yes	No
Scheduling	Yes	No
Open/click tracking	Yes	Partial*

*Tracking via SMTP works for open tracking (pixel injection) but link wrapping for click tracking requires the tracking header to be set.

---

Troubleshooting

Authentication failed — Verify your API key has sending_access scope and is not expired.

Domain not verified — The From address domain must be verified. See Domains.

Connection refused — Ensure your network allows outbound connections on port 587. Some cloud providers block this by default (e.g., AWS EC2 — use the REST API instead).

STARTTLS required — You must call STARTTLS before authenticating. Set secure: false and enable STARTTLS negotiation in your client.