Cold email domain setup: a practical checklist

Before the first outreach message goes out, the domain behind it needs to be chosen, authenticated and checked. This checklist walks through that order, with a free tool for each step.

CheckMX guide · Published October 27, 2026 · For the broader background, read the sending setup guide.

Start with the purpose

This guide is for wanted, lawful business email: outreach to people you have a valid reason to contact, with a clear sender identity and a working opt-out. It is not a way to hide who you are or to send at people who have not agreed to hear from you. Providers and recipients punish that behavior, and laws such as CAN-SPAM set requirements you must follow. Nothing here is legal advice or a promise of inbox placement.

1. Decide which domain to send from

Your main company domain carries your website, your customers’ replies and often your staff’s everyday mail. Outreach to new contacts carries more risk than ordinary correspondence, because strangers are more likely to ignore or complain about it. Many teams therefore send outreach from a separate domain or subdomain, such as a close variation of the brand name, so that a problem with outreach does not affect core company mail.

That choice has trade-offs. A separate domain protects the main one but starts with no reputation, and recipients may look at it with suspicion if it differs from your brand. Make it recognizably yours. Point its website or a simple page at your company so a curious recipient can verify who you are. Whichever route you pick, keep control of the registrar and DNS accounts and note the renewal date.

2. Create mailboxes with a real provider

A registrar and a mailbox provider are different services. Create real mailboxes with a business email provider and use a sender name that matches a real person. Provider admin tools list the exact DNS records they expect, so use those values rather than copying from another domain. Never paste mailbox passwords or recovery codes into an AI chat or into any form that does not need them.

Keep volume per mailbox modest and spread the sending across several mailboxes rather than pushing one hard. The CheckMX workspace includes mailbox warm-up and daily send safety caps for this reason; whatever tool you use, increase volume gradually and watch what happens.

3. Publish SPF, DKIM and DMARC

These three records let receiving servers check that mail claiming to be from your domain really is. Use your provider’s current instructions for the values, then confirm what is published.

• SPF lists the services allowed to send for your domain. Publish only one SPF record, and keep an eye on the limit of 10 DNS lookups. Check it with the SPF checker.
• DKIM signs outgoing messages. Your provider gives you a selector and a public key to publish. The DKIM checker can look up a selector you give it.
• DMARC tells receivers what to do when checks fail and where to send reports. Start with provider guidance, read the reports, and tighten the policy gradually. The DMARC checker shows what is published.

Google requires these three for bulk senders, as covered in bounce rate and spam rate limits. A lookup shows what is published; it cannot prove that a real message is signed correctly or that it will pass alignment, so send a test message to yourself and read the headers as well.

4. Check mail records and reputation

Use the MX lookup to confirm that the domain’s mail routing is what your provider asked for. Then check the sending IP against public blocklists with the blacklist checker. If your provider shares sending infrastructure, you may not know the IP, in which case leave that field blank and rely on the provider’s own dashboards. A listing is a reason to investigate; a clean result does not guarantee delivery.

5. Verify your list before the first send

A new domain has no history, so early bounces count for a lot. Consider checking your contacts first. Keep confirmed addresses together, handle catch-all (risky) addresses separately, and remove invalid ones. You can try a few addresses with the free email verifier, then upload a CSV of up to 10,000 unique addresses when you are ready.

6. Prepare the message and the opt-out

Use your real name, a clear subject line and a clear description of why you are writing. Include a physical postal address where the law requires it and a simple way to opt out. Keep a suppression list and apply it before every send. Treat an unsubscribe as final.

7. Start small and watch

Begin with a small batch to your most reliable addresses. Look at bounces and replies after a day or two, then increase volume in steps while the numbers stay healthy. If bounces rise, stop and re-verify the list. If people complain, revisit your audience and your message, not just your volume.

Checklist

1. Pick a recognizable outreach domain or subdomain, and secure registrar and DNS access.
2. Create real mailboxes with a business provider.
3. Publish and check SPF, DKIM and DMARC.
4. Check MX records and blocklists.
5. Verify the list and separate risky and unknown results.
6. Prepare a clear message, a postal address where required and an opt-out.
7. Warm up, start small and watch bounces and complaints.

Where CheckMX helps

CheckMX offers the free tools linked above, verification for single addresses and bulk CSV files, and a workspace for campaigns, a unified inbox and mailbox warm-up. Every plan, including the free Sandbox, comes with email checks. See CheckMX vs Hunter if you are weighing it against a broader prospecting tool.