The first cold email campaign I ran for a client had solid copy, decent targeting, a clear offer. It produced zero replies. Not a handful. Zero, across two weeks of sending.
When I finally checked the DNS records on the sending domain, the DMARC record was missing. About half the emails were silently failing SPF authentication. The other half were landing in spam because the domain had been set up the same afternoon the campaign launched, with no warm-up period and no prior sending history.
The copy never had a chance.
Cold outreach lives or dies in the infrastructure, not the subject line. Most people spend 80 percent of their setup time on copy and about ten minutes on the sending domain. The infrastructure side is boring and it is the whole ballgame.
Here is the five-step setup I run before any campaign reaches a real prospect.
Step 1: A Dedicated Domain for Each Campaign Type
Never send cold outreach from your main domain. This is the rule I repeat most often and the one most people skip because registering a domain feels like extra overhead.
It is not overhead. It is insurance.
Your main domain sits at the centre of your business email: invoices, contracts, the transactional messages your customers depend on. A single spam complaint spike from a cold campaign can damage deliverability across everything, including the messages that have nothing to do with outreach. Cold email is inherently higher-risk because you are sending to people who did not opt in. Some will hit spam rather than unsubscribe. Your main domain should never absorb that risk.
The fix is simple: register a domain specifically for outbound. Something close to your real domain but distinct, for example trycompanyname.com, yourcompany-outreach.com, or contact-yourcompany.com. I also keep one backup domain per campaign type so if one domain's reputation dips, I can rotate while the other recovers.
I manage these in Namecheap or Cloudflare. Roughly $12 to $15 per domain per year. The cost of burning your main sending domain is your entire email operation.
Step 2: DNS Records Before Anything Else
I wrote about SPF, DKIM, and DMARC setup in detail in an earlier post. Read that if you are starting fresh. For outreach domains specifically, here is what matters:
SPF tells receiving mail servers which IP addresses are authorised to send on behalf of your domain. When you connect a new sending account in Instantly.ai, the platform gives you the exact TXT record to add. Copy it exactly into your DNS.
DKIM is a cryptographic signature that proves the message was not tampered with in transit. Instantly.ai generates the DKIM keys when you add the account. You add two CNAME records to your domain's DNS, then verify inside the platform before any sending starts.
DMARC tells mail servers what to do when SPF or DKIM checks fail. Start with p=none (monitoring-only) on a new outreach domain, then shift to p=quarantine once warm-up is done and your data shows legitimate mail passing cleanly.
None of this takes more than 20 minutes. Skipping it means roughly 15 to 25 percent of your emails fail authentication checks before they ever reach a spam filter.
Step 3: The Instantly.ai Warm-Up Setup
A brand-new domain, or one that has never sent at volume, needs to earn its sending reputation before it can handle campaign volume. You do that through warm-up: low-volume, automated email exchanges that build a sending history the major inbox providers can see.
Instantly.ai has a built-in warm-up feature under Email Accounts → [Account] → Warmup settings. Here is exactly how I configure it when I add a new outreach account:
- Enable warm-up: on
- Ramp-up increment: 2 to 3 additional warm-up emails per day (the platform increases the daily warm-up volume by this amount automatically)
- Daily warm-up emails: start at 5, let it ramp from there
- Warm-up reply rate: 40 to 50 percent (Instantly's network replies to warm-up emails at this rate, signalling real engagement to inbox providers)
The warm-up runs between real accounts in Instantly's network. Messages land in inboxes, get opened, get replied to. From Gmail's or Outlook's perspective, this domain sends email people respond to. That is what good sending reputation looks like.
Leave warm-up running for at least 14 days before you send a single cold outreach email to a prospect. For a completely fresh domain that has never sent anything, I prefer 21 to 28 days. The temptation to start sooner is real. Resist it.
Step 4: A Volume Ramp-Up Schedule
Even after warm-up, the transition from warm-up volume to campaign volume needs to be gradual. Jumping from 5 warm-up emails per day to 300 campaign emails the morning your campaign goes live is a fast way to end up in spam folders.
The schedule I follow for a new mailbox entering a live campaign:
- Week 1 of sending: 20 to 30 outreach emails per mailbox per day
- Week 2: 40 to 60 per mailbox per day
- Week 3: 60 to 80 per mailbox per day
- Week 4 onwards: up to the platform recommended ceiling (Instantly.ai recommends staying under 100 per mailbox per day for sustainable deliverability)
If you need to send at higher volume, add more mailboxes rather than pushing one account past its safe ceiling. Each additional mailbox goes through its own warm-up cycle before joining the campaign. Set the daily cap per mailbox inside Instantly.ai under Campaign → Schedule settings, not just as a mental note.
Step 5: Inbox Placement Test Before the First Send
Before a single campaign email goes to a real prospect, I run a placement test. I use mail-tester.com for a quick score, and GlockApps when I need to see which specific inbox folders the message is landing in across providers.
The process: send your actual first campaign email (the real thing, not a placeholder) to the test address the tool gives you. The tool shows you a deliverability score, whether SPF, DKIM, and DMARC passed, and often a breakdown of whether the message lands in primary inbox, promotions, or spam at the major providers.
A score of 8 or higher on mail-tester.com is the minimum I look for. If it comes back lower, the report tells you exactly what failed. Fix those items before the campaign goes live. Common failures this step catches: a missing or misconfigured DMARC record, an SPF record that includes too many IP ranges and looks suspicious, an image-heavy template that spam filters flag, or a blacklisted sending IP that Instantly.ai assigned to your account. If it is the last one, contact their support team. They will reassign the IP. It is a known issue and they handle it quickly.
The placement test is the moment before launch where there is still time to fix something. After the first 200 emails go out, you are managing reputation damage, not preventing it.
What the Pre-Flight Looks Like on Launch Day
Once the five steps above are complete, the remaining pre-flight check on the campaign itself is short. I verify the unsubscribe link is working and points somewhere real. I confirm the reply-to address is one I actually monitor. I check that the campaign schedule skips weekends for B2B sends, since weekend email to business accounts tends to perform noticeably worse on reply rate. And I open the first email in the sequence on a phone to confirm it renders correctly on mobile, since a significant portion of cold email opens happen on mobile and a broken layout reads as a spam signal to some filters.
That is the whole checklist. Most of the work is front-loaded into the domain registration, DNS setup, and warm-up window. Launch day itself should be low-stakes because the infrastructure decisions were made two to four weeks earlier.
If you are setting up Instantly.ai for the first time, troubleshooting a domain that has gone cold, or trying to figure out why a campaign that looks right on paper is not landing in primary inbox, drop me a line. The issue almost always shows up in the DNS or the warm-up timeline before it shows anywhere else.
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