The most expensive mistake in cold email is not writing a bad email. It is sending a good one from a domain that was never set up to send.
Nobody replies. You assume the offer is wrong, so you rewrite it. Still nothing. What actually happened is that your messages went to spam, or were rejected before delivery, and no bounce came back to tell you.
Work through this list before the first send. It takes an afternoon and it is the difference between a campaign and a waste of a month.
Domain and infrastructure
1. Send from a separate domain, never your main one.
If your business is acme.com, buy something like acme-mail.com or getacme.com and send from that. Cold email carries real reputation risk. If a domain gets burned, everything on it goes down with it, including the invoices and client replies you send from your normal address.
This is not optional. It is the single most important item on the list.
2. Let the domain age before you send.
A domain registered yesterday, sending cold email today, looks exactly like every throwaway spam operation. Give it at least two weeks, ideally longer, before the first send. Point it at a real page in the meantime.
3. Put a real website on it.
Not a parked page. A single page explaining who you are, with a link to your main site, is enough. Filters check whether the sending domain resolves to something real.
4. Set up SPF, DKIM and DMARC.
These three DNS records are how a receiving server verifies that you are allowed to send as your domain. Without them you are unauthenticated mail, and Google and Microsoft now reject or spam-folder that by default for bulk senders.
This is the technical core of deliverability, and it has its own guide because there is more to say than fits here.
5. Verify all three actually pass.
Setting the records is not the same as them working. Send a test to a checker like mail-tester.com and confirm all three show as passing. A typo in a DNS record is invisible until you look.
6. Set up a custom tracking domain, or turn tracking off.
Open tracking uses a pixel served from a domain. Most sending tools default to a shared one, used by thousands of other senders, some of whom are spammers. That shared domain's reputation becomes yours.
Either point a subdomain of your sending domain at the tracker, or turn open tracking off entirely. Honestly, for cold email, off is often the better call: open rates have been unreliable since Apple started pre-fetching images, and the pixel is a spam signal you are choosing to carry for data you cannot trust.
Mailbox setup
7. Warm up every mailbox before real sends.
A brand new mailbox that sends fifty emails on day one is behaving like a compromised account. Warm-up means starting at a handful per day and increasing gradually over three to four weeks, while the mailbox also receives and replies to mail.
Most sending tools have automated warm-up built in. Use it, and do not shorten it.
8. Keep daily volume low per mailbox.
Sending twenty to forty per mailbox per day is a common working ceiling. If you need more volume, add mailboxes, do not raise the per-mailbox number. Two mailboxes at thirty is far safer than one at sixty.
9. Fill in the profile properly.
Real name, real photo, a signature with a physical address and a working unsubscribe path. An empty profile is a signal.
10. Send from a real person, not info@ or sales@.
Role addresses get filtered harder, and they read as broadcast. hasan@ outperforms hello@ before a single word of the email is considered.
The list
11. Verify every address before you send.
A high bounce rate is the fastest way to destroy a sending reputation. Run the list through a verification service and remove anything invalid, risky or catch-all. Aim to keep bounces under two percent.
If you scraped the list yourself, verify it twice. Scraped data is stale by default.
12. Remove role and generic addresses.
info@, contact@, admin@, support@, noreply@. These bounce more, convert less, and are more likely to be spam traps.
13. Check for spam traps and stale data.
Addresses that have not been active in years can be repurposed as traps. Any list older than a few months should be re-verified before use.
The email itself
14. Write it like a person writing to one person.
Deliverability is not only technical. Filters read content, and recipients mark things as spam, which is the strongest negative signal there is.
The rules that matter:
- Plain text, or as close as you can get. No template with a header image and three columns. Nobody writes to a colleague in HTML.
- No links in the first email, or one at most. Multiple links in a first-contact email is a spam pattern.
- No attachments. Ever, in a cold email.
- Short. Under 125 words. If it needs to be longer, it needs to be a different email.
- Avoid the obvious trigger words, but do not obsess. "Free", "guarantee", "act now", "limited time", "click here". Modern filters are much more sophisticated than a keyword list, but writing like an advert is still a reliable way to look like one.
- One clear question at the end. Not "let me know if you'd like to chat". Ask something specific and answerable.
And the legal minimum
Not optional, and the rules differ by country:
- A working unsubscribe. Honour it immediately and permanently.
- A real physical address in the footer.
- Accurate From and Subject lines. No pretending to be a reply.
- Check whether your target country permits B2B cold email at all. Some jurisdictions require prior consent even for business addresses. Assuming the rules of your own country apply to your recipient's is how people get fined.
After the first send, watch these three
Deliverability is not a setup task, it is a maintained state.
- Bounce rate. Above two percent, stop and clean the list.
- Spam complaint rate. Above 0.1 percent, stop and change the message or the targeting.
- Reply rate trending to zero. Frequently the first visible sign that you have started landing in spam, because deliverability failures are silent by design.
If any of those move against you, pause everything and diagnose. Continuing to send while a domain is degrading is how a domain becomes unusable rather than merely underperforming.
Doing this properly takes about a week
Domain purchase, DNS, a landing page, mailbox creation, three to four weeks of warm-up running in the background, list verification.
That is genuinely most of the work. The writing is the easy part, and it is the part everyone spends their time on.
If you would rather not build it, this is what I set up: domain, authentication, warm-up, sequences and the sending infrastructure, configured and tested before a single real prospect is contacted.