The Notebook · Oct 13, 2026 · 6 min read
by Marcus Oyelaran
Every few months a client forwards me a LinkedIn post about some new cold-email framework — multi-threaded pain funnels, whatever this quarter's name for it is. And every few months I ask the same question: when's the last time you checked whether your emails are arriving at all? The framework matters less than the delivery. A brilliant sequence in the spam folder has a reply rate of exactly zero.
Last year we took over outbound for a 19-seller company (you can read the full story in our Cartage Labs case study). Their reply rate was 1.1%. Their copy was fine. Their list was decent. Their emails were vanishing — about one in three straight to junk, and nobody had noticed for what looked like two quarters. Two quarters of "the sequence isn't working" meetings, held about a DNS record.
We run this on every outbound engagement now. It takes a day if your IT person is cooperative and a week if they're on vacation, which they always are.
1. Authenticate your domain — SPF, DKIM, DMARC. Three DNS records. SPF says which servers may send as you; DKIM signs the message; DMARC tells receivers what to do when the first two fail. If your DMARC policy is set to p=none, you have a smoke detector with no battery. Set it, monitor the reports for a month, then tighten. The Cartage Labs fix, for the record, was a DMARC record pointing at a dead reporting address from a 2021 rebrand. Three days to find. One line to fix.
2. Send cold email from a subdomain. If outbound tanks the reputation of mail.yourcompany.com, your invoices and your CEO's calendar invites go down with it. A subdomain is a fire door. Yes, it costs you a bit of brand recognition in the sender line. Cheap insurance.
3. Warm it up before you scale. Two to four weeks at low volume, sending to people likely to reply, before you touch your real list. Reply rate matters more than open rate here — replies are the strongest "this is a human" signal the filters get. Which leads to:
4. Write something worth replying to. Short, plain text, one ask, no tracking pixel, no three-image signature. The fancy HTML template your agency loves is a spam flag with a logo on it. And if the offer itself is weak, deliverability just makes more people ignore you faster.
5. Clean the list like it owes you money. Every address that hard-bounces is a mark against the domain. Verify before the first send, and remove non-responders after four or five touches — not out of politeness, out of self-defence. A decaying list quietly poisons everything sent after it.
6. Check the inbox placement, not the send report. Your sequencing tool will happily report a 97% "delivered" rate. Delivered to the junk folder counts. Seed your own test inboxes across Gmail, Outlook and a corporate filter, or use a placement tool, and look there once a month.
At Cartage Labs: reply rate 1.1% to 4.7% in ten weeks, meetings booked per month up threefold. I'd love to claim the copy rewrite did that. The honest split is maybe 60% plumbing, 40% words. The plumbing is the part everyone skips because it's dull and mildly technical, which I've come to think of as our competitive advantage: our clients' competitors keep skipping it too.
Deliverability isn't a one-time fix — filters re-score constantly, and a domain that's clean in March can be junk in September if volume and replies shift. We re-check placements quarterly on every active engagement, and roughly one in five checks turns up something. Also, some of this is out of your hands: corporate spam filters are capricious, and a perfect setup still won't reach a few percent of inboxes. If a consultant promises you 100% inbox placement, keep a hand on your wallet.
If you want the whole thing as a printable checklist, it's in the resource library with the rest of our playbooks — ungated, because we'd rather you fixed your DNS than admired our lead magnet.