The dos and don’ts of cold email outbound

Cold email has been declared dead more times than the fax machine. Yet, somehow, it keeps finding its way back into our inboxes. Every few years, new tools, new tactics and new privacy rules shake things up - and the debate starts again. Does it still work? Is it worth the risk? Or has the channel become so saturated, and so tightly policed by spam filters, that it’s more trouble than it’s worth?

The truth, as with most things in marketing, sits somewhere in the middle. Done well, cold email remains one of the few ways to reach decision-makers directly - a personal message, not an algorithmic guess. Done badly, it can burn your reputation faster than you can say “unsubscribe”. At Disruptive Thinking, we’ve seen both sides. We’ve seen campaigns that quietly bring in qualified leads and open doors that paid ads never could. And we’ve seen others that hurt brand trust, deliverability and morale in equal measure. So, here’s what we’ve learned about when cold email is worth it, when it’s not, and how to approach it without wrecking your domain (or your reputation).

The myth of easy returns

There’s a reason cold email refuses to die - because it can work. Top-performing campaigns - the ones that sound human and actually add value - still see reply rates of 15 to 25 per cent, sometimes even higher. Even a handful of positive replies can be worthwhile if your deals are high value or long-term. But those campaigns are the exception, not the rule. Across the industry, the average open rate for cold outreach in 2025 has dropped to around 27 per cent, down from roughly 36 per cent two years ago. Replies are in the low single digits. That means that for every hundred emails you send, maybe one or two will turn into a real conversation. So, whether cold email pays off depends on what you sell, the value of each deal, and how much time you’re willing to invest.

If you’re offering consultancy, enterprise software or specialist B2B services, a few meaningful conversations can justify the effort. But if your product is low-value or your approach is high-volume, you’ll spend more time cleaning data and chasing replies than you’ll ever get back in revenue. Cold email isn’t cheap anymore. It takes research, testing, and a careful hand. Treat it like a quick fix and you’ll end up disappointed. Treat it like a craft - deliberate, respectful, and patient - and it can still pull its weight.

Deliverability: the invisible gatekeeper

Here’s the thing about cold email - your beautifully written message means nothing if no one ever sees it. Modern spam filters are ruthless. They don’t just look at what you’ve written, they look at everything behind it: how many emails you’ve sent, how often, from what domain, whether that domain is trusted, and if your recipients are opening or deleting. This is where most cold email efforts fail before they even start. Your sender setup needs to be watertight. SPF, DKIM and DMARC records aren’t optional anymore - they’re the basic passport that tells inboxes you are who you say you are. A missing record here can mean your emails quietly disappear into spam purgatory. Then there’s the domain itself. Smart teams now use dedicated subdomains for outbound (think hello.yourbrand.com or outreach.yourbrand.com) and warm them up gradually. That separation protects your main brand domain from being blacklisted if things go wrong. It might sound technical, but in practice, this step is what separates professionals from spammers. If you’re not landing in inboxes, the rest doesn’t matter.

The human side of the inbox

Let’s talk about tone. Cold email often fails not because of poor deliverability, but because it forgets the person on the other side. Nobody enjoys feeling like a data point in a sequence. We all know what it’s like to open an email that pretends to be personal but clearly isn’t. The best cold emails don’t try to trick anyone. They’re written like a real human reaching out to another human - clear, short, relevant and kind. A good one might reference something recent or specific: a funding round, a product launch, an article the person’s company shared. It asks a question or makes an observation that feels natural. It never oversells. It’s the start of a conversation, not a pitch. And when you follow up (you should), do it with empathy. A gentle nudge, a different angle, a reason for the follow-up. If you’ve sent two or three emails and heard nothing back, that’s your answer. At its best, cold email is like walking up to someone at an event and introducing yourself politely. At its worst, it’s the digital equivalent of shouting across the room and hoping someone looks up.

The ethics and the risk

Cold email operates in a grey zone - part legitimate outreach, part potential nuisance. Even when it’s legally compliant under GDPR or PECR, it can still backfire if it feels invasive or irrelevant. Spam complaints don’t just hurt your ego; they actively harm your sender reputation, making future emails (even legitimate ones) harder to deliver. And the damage isn’t just technical. If you run a small business, your brand is personal. Once your name becomes associated with spam, it’s hard to shake. That’s why separating your cold email activity from your main domain is a smart insurance policy.

Our golden rule: if you wouldn’t be comfortable receiving it, don’t send it.

Keep things transparent - say who you are, why you’re getting in touch, and how they can opt out. If you’re building trust, you’ll often get a polite “not right now” rather than a spam report.

Why people still do it

So with all this hassle, why does anyone bother? Because cold email still offers something few channels can - control. You decide who to reach, when to reach them, and what to say. You don’t have to wait for algorithms or ad budgets to work in your favour. For niche B2B markets, it’s one of the few ways to directly approach decision-makers. And when combined with content, events, or LinkedIn outreach, it can form part of a thoughtful, multi-touch strategy. Done right, it’s not about interruption. It’s about connection. We’ve seen founders secure investor meetings, agencies build partnerships, and sales teams reignite lost conversations - all through one well-written email that landed at just the right time. It’s rare, but it happens. And when it does, it’s magic.

The new anatomy of success

Today’s most effective cold emails share a few common threads. They’re short, genuine, and written with a clear sense of empathy. No big images. No attachments. No “Hi {name}, I hope you’re well” unless you actually mean it. A good email feels like the start of something. It asks a small question. It invites conversation. It makes it easy to say yes. You don’t need to over-engineer it. You just need to care about relevance more than volume. And while you’re at it, watch your timing. Two follow-ups are usually plenty - spaced a few days apart. Any more, and you risk crossing the line from persistent to pestering.

Measuring what matters

What you measure shapes how you behave. Open rates are no longer the full story - Apple’s privacy updates made them unreliable. So focus instead on replies, bounce rates, and conversions. A high open rate but no replies? Your copy or targeting needs work. Good replies but few meetings? The follow-up or offer probably needs adjusting. Aim for a bounce rate below five per cent. Anything above that suggests poor data or reputation issues. And if more than one in ten people unsubscribe, you’re talking to the wrong audience. But the most important number of all? ROI. How much time and money went in, and what came out the other end. Without that, cold email is just another marketing myth - activity without accountability.

Cold email as part of the mix

The biggest mistake we see is treating cold email as a standalone tactic. It’s far more powerful when used alongside other touchpoints. Imagine sending an email to someone who’s already seen your brand on LinkedIn, read your content, or met you at an event. Suddenly, your message isn’t cold at all - it’s warm, relevant and familiar. That’s where cold email shines. Not as a megaphone, but as part of a conversation that already has context. So if you’re thinking about building outbound into your growth strategy, make sure it connects with the rest of your ecosystem. Use it to amplify your voice, not replace it.

So… does it still justify the means?

It depends on how you approach it. If you’re prepared to do the groundwork - the authentication, the targeting, the testing - and if you respect the person on the other side of the screen, then yes, cold email can still be a smart, scalable channel. But if your plan is to load up a list and hit send, save yourself the trouble. It’ll cost you more than it earns you. Cold email isn’t dead - it’s just grown up. It demands the same care and craft you’d give any other part of your marketing mix. Done right, it opens doors. Done wrong, it closes them.

A question to leave you with:

When was the last time you opened a cold email and actually wanted to reply? If you can’t remember, maybe that’s exactly where to start.