Configure SMTP credentials — SESMetric

SESMetric exposes a standard SMTP relay at smtp.sesmetric.com. Any framework, language, or mail client that speaks SMTP works without changes.

1. Create an SMTP user

In the dashboard go to SMTP → Add credential. Pick a name (e.g. prod-app). You'll get a username and a one-time password — copy them now; the password is not stored in clear text.

2. Connection settings

Setting	Value
Host	`smtp.sesmetric.com`
Port	`587` (STARTTLS) or `465` (TLS)
Username	from dashboard
Password	from dashboard (one-time)
Auth	LOGIN / PLAIN over TLS

Port 25 is open for internal-network senders but blocked on most cloud providers.

3. Example — Node.js with nodemailer

import nodemailer from "nodemailer";

const transport = nodemailer.createTransport({
  host: "smtp.sesmetric.com",
  port: 587,
  secure: false,
  auth: { user: process.env.SM_USER, pass: process.env.SM_PASS },
});

await transport.sendMail({
  from: "no-reply@example.com",
  to: "alex@customer.com",
  subject: "Welcome",
  html: "<p>Welcome to Example.</p>",
});

4. Example — Python with `smtplib`

import smtplib, ssl
from email.message import EmailMessage

msg = EmailMessage()
msg["From"] = "no-reply@example.com"
msg["To"] = "alex@customer.com"
msg["Subject"] = "Welcome"
msg.set_content("Welcome to Example.")

with smtplib.SMTP("smtp.sesmetric.com", 587) as s:
    s.starttls(context=ssl.create_default_context())
    s.login(os.environ["SM_USER"], os.environ["SM_PASS"])
    s.send_message(msg)

5. Troubleshooting

535 authentication failed — verify the username + password were copied without trailing whitespace.
421 too many connections — paid plans get higher concurrency; free is capped at 5 simultaneous connections.
DKIM/SPF failing in deliverability reports — make sure the From: domain is a verified identity in your dashboard.

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