Private sending networks or more domains? Two deliverability bets, one budget

Cold email infrastructure spend splits into two camps, and I keep watching people pick a side based on whichever operator they follow this month, not on their own actual sending volume or their own actual deliverability data.

Two camps, one budget

Eric Nowoslawski, founder of Growth Engine X and one of the highest-volume Clay partners in the space, posted on LinkedIn about his team testing four separate private sending networks for cold email, evaluating providers away from the shared-IP infrastructure most teams default to.

Jesse Ouellette, founder of LeadMagic and one of the loudest deliverability voices on the topic, has argued the opposite instinct for years: skip the infrastructure arms race and maintain 10 to 15 backup domains instead, so no single domain's reputation is a single point of failure.

Neither one is selling snake oil. They're both operators who've sent enough email to have earned an opinion. That's exactly why the disagreement is worth sitting with instead of picking whichever name is louder in your feed this week.

What each cold email deliverability strategy is actually solving

It's worth being precise about what each operator has actually earned the right to say. Nowoslawski's Growth Engine X sends at a scale, publicly cited at over a million emails a month, where infrastructure decisions get tested against real reputation data every single day. Ouellette runs LeadMagic and writes the LeadMagic Alchemy newsletter, one of the more widely read deliverability publications in the space, drawing on patterns across a large number of client sending setups rather than one operation's own volume. Different vantage points, both legitimate, both worth weighing against your own situation rather than treating either as a universal rule.

Here's the thing both camps agree on, even if neither says it that way: a single point of failure is the enemy. A prototype domain is not a production sending system. One domain, one IP, one reputation score, and one Microsoft or Google policy update away from your whole pipeline going dark. Nowoslawski and Ouellette are proposing two different ways to stop being that fragile. They are not actually arguing about the goal.

The number nobody's saying out loud

Worth noticing: Ouellette's own reply-rate target sits close to three times the current market average, per Instantly's 2026 numbers, the same benchmark behind our breakdown of where cold email replies actually come from. That gap says less about his advice being wrong and more about how far the market has drifted since domain diversification became standard practice. A benchmark built for an easier deliverability environment is still the goal, even as the environment gets harder underneath it.

That's not a knock on either operator. It's a reminder that even good advice ages, and the infrastructure debate happening right now is downstream of a market that's gotten measurably tougher since either of them first published their playbook.

It also helps to know what 'good' looks like on the numbers that actually gate deliverability, not just reply rate. Instantly's 2026 benchmark puts the top quartile of senders at a 5.5% reply rate and elite senders above 10%, with Google's 2026 sender guidelines treating anything above a 0.3% spam complaint rate as a hard line, 0.1% as the real target. Both Nowoslawski's and Ouellette's approaches are ultimately bets on staying under that spam threshold at scale. Neither one is a shortcut around it.

The right cold email deliverability strategy depends on your volume

There's a failure mode specific to each side worth naming plainly, because it's the one that actually costs teams money. On the domains side, the failure is sprawl without hygiene: a team stands up fifteen domains, sends from all of them, and never re-verifies which ones are still healthy, so the redundancy that was supposed to protect them instead multiplies the number of things that can quietly go wrong at once. On the network side, the failure is over-engineering before the volume justifies it: a team pays for isolated infrastructure they could have gotten most of the benefit of with disciplined domain rotation, and the fixed cost sits there as overhead against a sending volume too small to need it.

Private networks and domain diversification are not actually competing for the same budget. They solve different failure modes. A private network protects you from the shared reputation pool. More domains protect you from a single domain's mistake taking down your whole operation. Below a few hundred thousand sends a month, extra domains are the higher-leverage dollar: cheap, fast, and forgiving of mistakes while you're still learning your own sending patterns. Past that volume, where a single bad domain event costs real pipeline and a bad shared-IP neighbor can drag your whole block down with it, the case for a private network's isolation starts to justify its cost.

You're not behind if you're still on the domains side of this. Most teams are, and most teams should be, until volume forces the question.

Context on where that question actually kicks in: Growth Engine X, Nowoslawski's own operation, is publicly known for running over 1 million emails a month through Clay-powered outbound. That's the scale where a private network's fixed setup cost stops being a rounding error and starts paying for itself in fewer domain casualties. Most teams reading this are nowhere near that volume, which is exactly why the domains-first advice is the right default, not the consolation prize.

There's a hybrid option that gets talked about less than either pure camp: run domain diversification as the baseline for every team regardless of size, since it's cheap enough to be table stakes, and treat a private network as a later-stage infrastructure decision reviewed quarterly against actual send volume, not adopted preemptively because a founder you admire is testing one. That framing turns a binary either-or debate into a sequence, which is closer to how most infrastructure decisions should actually get made.

Neither failure mode shows up immediately. Domain sprawl looks fine for months until one bad list burns a domain nobody was actively monitoring, and by the time it's caught, the damage has already spread to whatever else was sending alongside it. Premature network investment looks fine too, right up until someone asks why outbound cost per meeting is double what it should be, and the answer turns out to be infrastructure the team never needed at that volume. Both mistakes are cheap to avoid and expensive to unwind, which is the real argument for matching the infrastructure to the volume you actually have, not the volume you're planning for next year.

One more angle worth considering before you spend anything: the two approaches aren't mutually exclusive, and framing this as an either-or debate is partly an artifact of how the two operators talk about their own work, not a technical constraint. A team already running a disciplined domain rotation can layer in a single private network for its highest-volume, highest-stakes campaigns while keeping everything else on the cheaper domain-diversification model. That hybrid is more operational complexity than picking one lane, which is exactly why most teams don't reach for it until volume and stakes both justify the extra coordination.

Do this instead of picking a side

Count your current monthly send volume before you read another hot take from either camp. If you're not already running the domain-diversification playbook, Microsoft's 2026 bulk sender crackdown makes that the more urgent fix regardless of what you do next. If you're past the volume where a private network pencils out, that's a conversation worth having with whoever runs your cold email program, not a decision to make off a LinkedIn post. Either way, run a deliverability audit before you spend on new infrastructure. Most teams find their actual bottleneck is list quality, not sending architecture, no matter which camp they end up in.

Revisit the decision on a schedule, not just once. Volume grows, Microsoft and Google keep tightening enforcement, and an infrastructure choice that was right six months ago is worth checking against where your sending actually sits today, not defended out of habit because it was right when you made it.

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