There’s a Reddit thread in r/Emailmarketing titled “Is Email Warmup Just a Bullshit Echo Chamber?” and it’s one of the most upvoted things in that community, because everyone running cold email has wondered the same thing. You pay for warmup (or it’s bundled into your sending tool), you watch the fake engagement numbers tick up, and you wonder: is this doing anything, or am I paying for a simulated friendship between my mailboxes?

Here’s my honest answer after running warmup across client infrastructure at KomsGro, reading both sides of the argument, and rebuilding our setup after Google’s 2024 bulk sender rules: warmup as most people practice it is partly theater. Warmup as it actually works is still essential. The confusion comes from the fact that these are two different things wearing the same name.

What warmup actually does (the mechanism)

A brand-new mailbox has zero sending history. Mailbox providers (Google, Microsoft) treat unknown senders with suspicion by design: they watch whether your emails get opened, replied to, moved out of spam, or deleted unread. Warmup is the process of generating positive engagement signals before your real campaigns start.

The mechanism that matters isn’t the warmup tool’s artificial opens. It’s this: providers build a reputation profile from your sending pattern. A mailbox that starts small (10 to 20 emails a day, mostly to engaged addresses), gets replies, and never gets marked spam builds a clean baseline. A mailbox that blasts 50 cold emails on day one gets flagged before it has a reputation to defend.

That part is not controversial, and it’s the part warmup tools genuinely help with: the ramp schedule, the automatic removal from spam, the engagement simulation. Where the echo-chamber criticism lands is on the cargo cult around it.

Where the skeptics are right

The “warmup is bullshit” crowd has real evidence, and I take three of their points seriously:

  1. Warmup does not fix a bad list or bad targeting. The most common misuse: a team burns a domain with terrible list hygiene, adds “more warmup”, and is confused when nothing improves. Warmup builds the floor; it doesn’t fix what you send.
  2. Warmup networks have quality problems. Your warmup emails land in other users’ inboxes. Some warmup networks include low-quality or spam-adjacent participants, and providers have gotten better at detecting artificial engagement circles. A warmup network that’s itself flagged can hurt you.
  3. It can create false confidence. I’ve seen teams “pass warmup” (great scores in the dashboard) and still land in spam on day one of real campaigns, because warmup engagement doesn’t model real cold outreach: cold emails to strangers with links get treated differently than warmup emails to engaged contacts.

What changed with Google’s 2024+ sender requirements

Google and Yahoo’s bulk sender rules raised the baseline for everyone: SPF, DKIM and DMARC authentication became effectively mandatory for bulk senders, spam complaint rates got explicit thresholds (keep under 0.3%), and one-click unsubscribe became expected for marketing volume. This didn’t make warmup obsolete; it made the fundamentals matter more than the warmup tool. In 2026, a perfectly warmed mailbox with no DMARC record still loses. Conversely, a properly authenticated domain with a sane ramp rarely needs heroic warmup.

The setup that matters more than the warmup tool

Since the debate above is about warmup specifically, here’s the deliverability stack in priority order, because warmup is only one line of it:

  1. Authentication. SPF, DKIM, DMARC on every sending domain. DMARC especially: it’s the one Google’s sender rules made de facto mandatory, and a missing DMARC record undermines everything else. This is a 30-minute setup and no warmup tool substitutes for it.
  2. Domain hygiene. Secondary domains (never your main one), registered for 2+ years, with real-looking names, redirecting to your main site so anyone who checks who you are lands somewhere real.
  3. Mailbox structure. 2 to 3 mailboxes per domain, warmup on each, campaigns never pointed at your primary company domain.
  4. Warmup ramp. 2 to 3 weeks for new mailboxes, native or standalone.
  5. List verification. Bounce rates under 2 to 3 percent. Verification runs before every list, every time.
  6. Content discipline. No spam trigger words doing heavy lifting, one link maximum in a first touch, plain text over heavy HTML.

Notice warmup is line 4 of 6. Teams that skip lines 1 to 3 and buy warmup tools are buying step 4 of a process they haven’t started. That’s the echo chamber the Reddit critics are pointing at.

What I actually do (and recommend)

The setup that has survived every client build:

  1. Authentication first. SPF, DKIM, DMARC on every sending domain. This is non-negotiable and does more for deliverability than any warmup tool.
  2. Warmup for 2 to 3 weeks on new mailboxes, run through your sending platform’s native warmup (Instantly and Smartlead both include it now) or a dedicated tool. Not because the artificial engagement is magic, but because it enforces the correct ramp schedule.
  3. Seed real human interaction into warmup where you can. A few real colleagues replying to real messages from the new mailbox beats any simulated network. I have every team member send a handful of genuine internal and friendly-external emails from new mailboxes during warmup.
  4. Ramp campaigns slowly. 20 to 30 per mailbox per day in week one of campaigns, up to the 50 ceiling. The warmup tool’s dashboard saying “healthy” is not permission to jump to full volume.
  5. Watch the real signals after launch. Bounce rate under 2 to 3 percent, spam complaints near zero, and replies arriving. If replies show up in the recipient’s spam folder, warmup passed but your content or list is tripping filters.

So, does warmup still work?

Yes, with a corrected definition: warmup is the ramp, not the engine. The tools that sell warmup as a deliverability fix for bad lists are selling noise. But the discipline warmup enforces (new domains don’t blast, authentication is set, volume ramps with reputation) is exactly what keeps cold email programs alive in 2026. The echo-chamber critique is aimed at the cargo cult; the practice, done honestly, still does its job.

The version I run at KomsGro for clients: authentication on every domain, 2-to-3 mailboxes per domain, native warmup for 2 to 3 weeks, slow campaign ramps, and daily monitoring of bounces and replies. It’s boring, and it’s why our clients’ domains stay alive month after month.

This sits inside the bigger outbound marketing system we run, next to the mailbox-per-domain math and the sending-volume limits. The setup is the foundation; the targeting is the house.

The “90% deliverability” claim (and why to distrust it)

A thread that keeps resurfacing in the cold email communities: a platform published claims about hitting 90%+ deliverability, and the practitioners pushed back hard. The pushback is right about the measurement problem: “deliverability” claims usually mean “inbox placement on our own seed tests”, which is not what happens when your real campaign hits 500 strangers.

What actually predicts whether a real cold email lands in the primary inbox:

  1. The recipient’s history with your domain. A prospect who’s received (and ignored) three of your emails before treats the fourth differently than a first touch.
  2. Your content fingerprint. Links, images, and spam-trigger phrasing matter per-email, not per-domain.
  3. Provider-specific reputation. Gmail and Outlook score you separately; you can be healthy at one and struggling at the other, which is why placement tests run across providers.

So when a tool advertises a deliverability number, ask what was measured. Warmup dashboards measure the warmup network’s behavior, which is the easiest audience in the world to look good to. The number that matters is where your real campaigns land at real providers for real prospects, and no warmup dashboard measures that.

Quick answers

Do I still need warmup if my domain is old? Less of it, but authentication and a short ramp still apply. Old domains with clean histories start from a better baseline, but cold outreach volume is still a new behavior pattern for that domain. Can warmup hurt me? Yes, if the network is low quality or if you run two warmup tools on the same mailbox simultaneously (conflicting signals confuse the pattern). One warmup source per mailbox, from a reputable tool. How do I know warmup worked? Seed-test real campaign emails to your own addresses at Gmail and Outlook before launch. Primary inbox placement at both is the pass condition; a green warmup dashboard alone is not.