RE:markable is the weekly email about emails. Dropping the latest email marketing news, updates, insights, free resources, upcoming masterclasses, webinars, and of course, a little inbox mischief.
Most marketers find out that their deliverability is broken three months (or even worse 3 years) after it’s already cost them thousands.
But, here’s the thing - deliverability doesn’t just fall off a cliff randomly due to your tech setup.
It erodes (and dies) slowly because of strategic blind spots. The way you acquire, send, and measure emails impacts your deliverability over time, until it decides to tank and you slip into full-blown panic mode.
The things you might not think matter, like how you collect your data, what you send, and who you send it to, are all ticking away in the background and killing your email deliverability if you’re not being strategic and intentional.
Fortunately, it’s fixable… but only if you know what’s really causing it.
Let’s take a look at the 5 invisible factors killing your email deliverability and how to fix them.
It kind of sounds like the beginning of a post-apocalyptic drama, right?
But this is the root cause of most deliverability issues, and that’s because it’s so easily overlooked or neglected.
Not all subscribers are equal, so you shouldn’t be treating them like they are.
Think of it this way… how many times have you signed up to a mailing list for a convenient discount code, one-off download, or quick enquiry?
And how many times do you then subsequently ignore the emails from that sender, send them to your bin, or complain about spam because you’re not remotely interested in anything else they have to offer?
It’s the difference between a consequential versus an intentional opt-in:
Consequential opt-in: Implied consent (even if someone didn’t agree to receive marketing emails), such as when someone makes a purchase or downloads a resource. They expect transactional or service-related emails, but not marketing content.
Intentional opt-in: Also known as explicit opt-ins, as someone is clearly agreeing to receive marketing emails, such as ticking a box or confirmation link during a double opt-in process.
The first type tends to mean lower engagement and higher spam complaints, whilst the latter is likely to mean higher engagement and lower spam rates.
New data burns quickest because there’s zero warm-up, no clear segmentation, and no clear value exchange.
It’s a fast track to damaged sender reputation and accelerated deliverability issues in the long term.
What you need to do:
Tailor your onboarding and welcome journeys for each list entry point. You need to warm up new contacts slowly, prioritising intentional opt-ins.
Remember that poor data in = poor deliverability out!
Alarm bells should be ringing loudly if this is the case because it’s a massive risk, especially for B2B.
If you’re sending all of your emails — cold outreach, transactional, marketing, support — through the same domain (e.g., @company.com), you could ruin your deliverability across the board.
Yep, your marketing, sales, and service teams could all be seriously affected by this risk because your sender reputation is damaged under the same umbrella!
Each type of email will have different engagement patterns, frequency, and reputation signals.
If you’re sending out a transaction message like a password reset, you absolutely need perfect deliverability. But if it’s being sent from the same domain as your cold outreach, which gets poor engagement and high complaints, there’s a good chance it’ll go straight to spam.
You shouldn’t be sending cold campaigns from the same domain as your main brand; otherwise, your reputation will already be compromised.
What you need to do:
Don’t send all of your emails from the same domain (kind of obvious after everything we just covered, but still!). Domain architecture = deliverability architecture.
EEEEEK [that’s the sound of the brakes being slammed].
A fresh start ≠ a free pass.
Email service providers (ESPs) might not carry over sender reputation, but your domain does, plus you'll be using a new IP and we know any change = deliverability impact.
Whether you’re switching to HubSpot or Klaviyo or anything in between, don’t mistake a new platform for a shiny new reputation, as ISPs keep tracking your domain’s reputation and engagement behaviour, regardless of which tool you opt for.
The worst possible thing you can do is switch to a new platform and blast your email list to hell because it immediately kills trust signals.
You need to warm up when moving IP - it's a BIG job and migration is heard. Plus opens and clicks are measured differently from each provider.
Also, if this has happened to you (opens and clicks tank after moving ESP), this blog might help here.
What you need to do:
Don’t skip a rewarming plan! Start with your most engaged subscribers and gradually increase your email volume to “warm up” your domain and new IP's to indicate healthy engagement. Remember to clean your email list before migration, too, and leave out dormant, unverified, or risky contacts.
Chasing the wrong metrics is a one-way ticket to major deliverability issues.
Why? Well, because you’re unintentionally masking the root issues behind your deliverability, because everything you’re measuring is telling you that you’re doing things right.
A high deliverability rate can still be deceitful because it doesn’t always include when your emails aren’t landing in the main inbox.
Don’t even get me started on open rates (the bane of my existence) and click rates, both of which are skewed by multiple factors such as privacy protections, brand recall, accidental actions, and even image caching.
In short, if you rely on the wrong metrics, you’re getting a superficial picture that could be masking some serious problems (you’re measuring symptoms, not causes).
What you need to do:
You need to focus on better indicators:
From marketers and CRM managers to B2B and B2C business owners, we’re all guilty at some point of prioritising content above all else.
Which means that while most of us will have a content calendar, we likely don’t have a solid and intentional email strategy.
Knowing your email deliverability status requires strategy because you need to monitor signals, review your domains, and adjust your cadence based on engagement and spam rates.
You can’t simply rest on assuming that deliverability “sits” in your ESP or IT because it is a marketing discipline. And just so you know, you CANNOT track deliverability in your ESP (HubSpot, Mailchimp etc).
You need to know your exclusion strategy, list hygiene, and risk levels by audience (e.g., cold, dormant, newly acquired, high-value), and frequently test, rather than doing one-off testing and assuming it’s sufficient.
What you need to do:
Embed deliverability into your wider email strategy, data management, and reporting. It’s a skill and a part of your marketing performance, not IT!
If you want to stay ahead, there are a few challenges to deliverability you should also keep an eye out for:
Remember: Deliverability evolves faster than most marketers can adapt. Staying ahead means monitoring new threats and evolving your strategy accordingly!
Associating your email deliverability with IT or as a technical issue is damaging your deliverability.
You need to focus on building a strategy that embeds deliverability into it, which means no more:
❌ Poor acquisition data
❌ Shared domains across teams
❌ Lack of migration strategy
❌ Wrong metrics
❌ Lack of a deliverability plan or an overall email strategy
If you haven’t audited your deliverability in the last six months, you’re already behind — don’t worry, it’s not too late to fix it, though!
I’ve helped over 40 businesses fix deliverability, protect their domains, and reclaim inbox visibility.
You can book a deliverability audit, or join my next deliverability masterclass to learn how to fix it properly.
RE:markable is the weekly email about emails. Dropping the latest email marketing news, updates, insights, free resources, upcoming masterclasses, webinars, and of course, a little inbox mischief.