Domain Setup

MX Record

After adding your domain to our system, you'll need to point it to our mail servers:

For a self-hosted instance, mx.stmp.ink is the hostname that resolves to the server running the SMTP receiver (port 25 in production, 2525 in local development). For local testing, skip DNS entirely and use the dev-verify toggle on the Domains page instead.

Setup Instructions

1. Log in to your domain/DNS provider's website
2. Find the DNS settings or Domain management section
3. Create a new MX record with exactly the values shown above

The dashboard also offers a one-click DNS MX auto-check that verifies the record is live once you've added it.

Please Note

DNS changes don't propagate instantly - it could take anywhere from a few minutes to 24+ hours depending on your DNS provider. If you've just updated MX records, expect spotty email delivery until propagation completes. Some providers like Cloudflare are pretty quick (usually a few minutes).

Using Subdomains

Subdomains work the same way as root domains.

In this example, both test.example.com and support.example.com would be configured to receive email.

Why Use Subdomains?

• Keep your root domain on its real email provider while test.example.com receives in the sandbox
• Separate concerns per subdomain (notifications, support, billing)
• Test email configurations without touching your main domain's reputation

Each subdomain must be added separately before configuring its MX records. For example, to use support.example.com and billing.example.com, you need to add both domains individually in your dashboard.

Setting Up a Subdomain

Let's say you want emails to arrive at help@support.example.com:

1. Add the subdomain in dashboard — Go to the Domains section of your dashboard and add support.example.com as a new domain
2. Configure DNS for the subdomain — Add an MX record for your subdomain:

3. Create a new Account — Create a new account and select the support.example.com as the domain name
4. Wait for DNS propagation — Once DNS propagation completes, you can receive emails at any address @support.example.com

Troubleshooting

If emails aren't arriving after updating your MX records:

• Verify your DNS configuration — Check your MX setup using Google's DNS Toolbox by entering your domain name. This tool will confirm if your MX record is correctly configured and visible across the internet.
• Ensure single MX record configuration — Your domain should have only one MX record pointing to mx.stmp.ink. Multiple or competing MX records will interfere with proper mail delivery. Remove any existing MX records from previous email providers before adding ours.
• Local testing? — Use the dev-verify toggle on the Domains page — it marks the domain verified without any DNS, so you can start receiving sandbox mail immediately.