To send cold email without hurting your main domain, send from a separate lookalike domain, set up SPF, DKIM and DMARC before the first email, warm up each new inbox for a few weeks, verify every address so you don't bounce, keep daily volume per inbox modest, write short emails to people with a real reason to hear from you, include an easy opt-out, and stop the sequence the moment someone replies or bounces.
Key takeaways
- Never send cold email from your main domain. Use a lookalike domain (for example getyourbrand.com) that redirects to your site.
- Set up SPF, DKIM and DMARC on the sending domain before you send anything.
- Warm up new inboxes for a few weeks, and keep daily volume per inbox low even after.
- Verify every address before sending. Bounces damage reputation faster than almost anything.
- Short, specific emails to people with a reason to hear from you get replies, not spam reports.
- Stop on reply, bounce or opt-out, every time, automatically.
Why domains get burned
Mailbox providers like Gmail and Outlook decide where your email lands mostly by reputation: the reputation of your domain, your sending servers and the content. Reputation drops when:
- many emails bounce because the addresses don't exist,
- people mark your email as spam,
- volume jumps suddenly from a new or quiet domain,
- authentication is missing or broken,
- almost nobody opens or replies.
When a domain's reputation drops far enough, its email goes to spam, and that includes your ordinary email: replies to customers, invoices, password resets. That's what "burning your domain" means, and it can take a long time to recover.
Google and Yahoo also have published requirements for bulk senders, including authentication, an easy unsubscribe and low spam-complaint rates. Even if you send far less than "bulk", meeting them is the safe baseline.
Step 1: use a separate sending domain
Buy one or two lookalike domains just for outreach. For a company at shiftly.com, that might be getshiftly.com or tryshiftly.com.
- Point the website at your real site with a redirect, so anyone who checks the domain lands somewhere legitimate.
- Create real inboxes for real people on it: roy@getshiftly.com, not sales@ or noreply@.
- Use the same name and signature as on your main domain, so replies feel continuous.
If the outreach domain ever gets into trouble, your main domain is untouched. This one step prevents most disasters.
Step 2: authenticate with SPF, DKIM and DMARC
These three DNS records prove the email really comes from you. Set them up on the sending domain before the first email. Your email provider (Google Workspace, Microsoft 365 or another) gives you the exact values.
| Record | What it does | What it looks like |
|---|---|---|
| SPF | Lists which servers may send for the domain | A TXT record starting v=spf1, including your provider |
| DKIM | Signs every email so receivers can check it | A TXT record at a selector your provider gives you |
| DMARC | Tells receivers what to do when checks fail, and sends you reports | A TXT record at _dmarc starting v=DMARC1 |
Start DMARC with a monitoring policy (p=none) and a reporting address, then tighten it once you're sure all your legitimate email passes.
Check your setup with a free DNS or mail-tester tool before sending. One typo in SPF can fail every email. More in cold email deliverability.
Step 3: warm up every new inbox
A brand-new inbox that suddenly sends 200 emails looks like a spammer. Warm-up builds a normal-looking history first.
- Start by sending a handful of normal emails a day, with replies and conversations.
- Raise volume gradually over a few weeks.
- Many teams use a warm-up tool that exchanges emails between real inboxes and marks them as important.
Even after warm-up, keep volumes modest per inbox. If you need to send more, add inboxes (and maybe a second domain) rather than pushing one inbox harder. Spreading volume across a few warmed inboxes is safer than one busy one.
Step 4: build small, verified lists
Who you email matters more than how you write.
Pick people with a reason. Intent signals give you that reason: they engaged with a competitor's post, their company is hiring for a role you help, they visited your pricing page, they asked for a recommendation in a public thread.
Verify every address. Run each list through an email verification service and drop invalid, risky and catch-all addresses when you can. A bounce rate of more than a few percent is a warning sign.
Keep lists small and specific. Forty people who all share one reason beat 4,000 people who share a job title. You can write one first line that fits all forty.
Follow the law. Rules differ by country. In the US, CAN-SPAM requires a physical address and a working opt-out. In the EU and UK, GDPR and PECR set stricter limits on who you can email and why. Check what applies to you.
Step 5: write short emails people answer
Good cold emails are short, specific and easy to reply to. A structure that works:
- The reason. One line on why you're writing to this person now.
- The point. One or two lines on the problem you solve, in their words.
- The ask. One small question, easy to answer.
For example (fictional):
Hi Dana, saw you liked Rotaly's post about Sunday-night scheduling. We built Shiftly for single-location diners that do the rota in a spreadsheet: staff swap shifts by text and you approve. Worth a look for Lakeview?
What to avoid:
- links in the first email (one at most), and no tracking pixels if you can help it,
- attachments,
- images and heavy HTML,
- "just following up" with nothing new.
Use 2–3 follow-ups at most, a few days apart, each adding something: a short case, a different angle, a direct question. Then stop.
Step 6: stop rules and monitoring
Automate the stops. Every sequence should end immediately for a person who:
- replies, in any way, including "not interested",
- bounces,
- opts out or asks not to be contacted,
- is already a customer or in an open deal.
Watch these numbers weekly per inbox:
| Number | What it tells you |
|---|---|
| Bounce rate | List quality. Rising bounces mean verify harder or pause |
| Reply rate | Whether the targeting and message work |
| Spam complaints | The most dangerous number. Pause if it rises |
| Opt-outs | Whether you're emailing the wrong people |
If something looks wrong, pause the sequence first and investigate second. A paused campaign costs a day; a burned domain costs months.
How Cosmo does this for you
Cold email is in Cosmo's one $99 plan. He sends from your own Gmail, Outlook or SMTP inboxes (up to 5), on separate warmed inboxes on a lookalike domain. He checks SPF, DKIM and DMARC before the first send, verifies every address, keeps daily volume modest, and stops on replies and bounces.
He builds lists from intent signals, writes a first line for each person, and sends each batch to you as an approval card: "Cold email to 60 diner GMs who engaged with a competitor's post. 3 steps, from roy@getshiftly.com. Approve?" Nothing sends without your yes. Replies come to your own inbox. Compare with a dedicated AI SDR on Cosmo vs Artisan.
One short email when a new guide is out. At most one a week.