What You Need to Know About Your Email Service Provider (That They Won’t Tell You!)

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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.

Let’s talk about something I don’t think gets said enough in email marketing:

Your email service provider (ESP) isn’t built to make you a better marketer.

It’s built to make you feel good about what you’re already doing.

If you’ve ever logged into your dashboard and seen glowing “email health” scores, colourful bar charts, or features like “send time optimisation”, it probably felt like you were smashing it.

The problem with these tools is that they aren’t designed with real (or evolved) email marketing in mind, which means that, really, they’re holding you back.

They’re software.

And most of them weren’t even designed by email marketers, experts, specialists and experienced pro's. 

So in this blog, I’m lifting the lid on what your ESP doesn’t tell you, how you might be measuring the wrong things, and the critical questions you need to start asking if you want to make smarter, more strategic email decisions.

Shared IPs & deliverability? You’re not alone (and that’s the problem)

When you send an email via your ESP, it doesn’t just leave from your domain.

It leaves from an IP address – think of it like your digital stamp of origin.

What your ESP won’t tell you is that you’re probably sharing that IP with hundreds, maybe thousands, of other businesses. 

This is called a shared IP, and while it’s fine in theory, your deliverability (how often your emails actually land in the inbox) is now being influenced by everyone else’s behaviour too. 

Yep, that means that the nasty little spam machines on your IP, churning out content flying straight to spam or being marked as junk, could be negatively impacting your own emails because the reputation is shared.

Unless your ESP is regularly rotating and refreshing these IPs (spoiler: a lot of them don’t), that damage sticks around like a dodgy tattoo.

Ask your ESP:

• How many users are on the same IP as us?
• Who do we share ours with? (sometimes ESP's will put new customers on a few and then move you to a 'good' or 'bad' depending on your practices) 
• Do you rotate IPs regularly?
• What’s the current reputation of our IP? (test it yourself with MX Toolbox or GlockApps)

“Email Health” scores are… misleading at best

• This is not your actual deliverability
• They cannot track your inbox placement - currently (written August 2025)

You could have a 99% delivery rate, but still land in Gmail’s spam folder every time.

The only real way to know where your emails land (primary inbox, promotions, spam) is to test it externally by using proper tools or monitoring sender reputation with Gmail Postmaster, Microsoft SNDS, or Yahoo feedback loops.

Ask your ESP:

• What data exactly do you use to determine “email health”?
• Can I segment delivery metrics by ISP (e.g., Gmail, Outlook, Yahoo)?
• Do you support inbox placement testing integrations?

Benchmarks are pointless - context is everything

I swear I’m not trying to hurt feelings, here, but it’s important to dispel some really harmful misconceptions.

A common feel-good feature in a lot of ESPs you might see is phrases like “Your open rate is 6% higher than industry average.”

But what does that even mean? Absolutely nothing! 

That’s because you have no idea what types of emails others are sending, or their list hygiene, or how they measure success, or even the industry that the data is based on.

Benchmarks really only make sense when you compare your performance to yourself over time with clear context, not generic industry averages.

Ask your ESP:

• How are these benchmarks generated?
• Can I create my own custom benchmarks by email type or list segment?

“Helpful” features that don’t always help

How many features fall under the “pretty to look at/read, but useless” category? ESPs love to roll out shiny new features, and some can be useful. But, more often than not, they’re doing more harm than good.

Let’s look at a few examples:

• Send time optimisation: Tries to send when someone is “most likely” to open based on past behaviour, but often clusters your sends into the same window as everyone else, which reduces your visibility and prominence.
• Resend to non-openers: Pushes more volume at people who’ve already ignored you. This doesn’t help your engagement signals and is more likely to hurt them.

• AI subject line generators: Often produce generic, high-risk language that increases spam probability. 

These features might sound great on paper, but they’re built for scale and simplicity, not relevance and nuance.

True insights and analytics rely on knowing the ‘why’, which means you need context… something that isn’t provided with many of these features.

Ask your ESP:

• What testing has been done on this feature’s effectiveness?
• Can we A/B test with control groups to validate improvements?
• How are you measuring long-term engagement vs short-term opens?
  
  
  

You’re tracking the wrong metrics

• Is email increasing branded search traffic?
• Is it improving reply sentiment?
• Is it moving leads down the pipeline?
• Is retention increasing among active subscribers?

Most ESPs don’t track this, but that doesn’t mean that you can’t! You can (and should) build that data story yourself.

👉🏻 Useful read: How to Start Using Email as an Awareness Channel
👉🏻 Useful read: Stop Relying on Email Opens & Clicks: Better Metrics for Email Marketing

So, what’s the real issue?

 
Questions you should be asking your ESP

Take back control, stop taking things at surface level, and start asking better questions:

Final thoughts from Beth

Your ESP is a delivery engine, not a strategy engine.

It’s our job as email marketers to look beyond features and actually interpret data and analyse it in context. 

If you’re relying on ESPs to tell you what success looks like, you’re only getting half the story.

The best marketers are the ones who challenge the defaults, look beyond the dashboard, and know how to separate feel-good features from the real impact metrics.

And if you want help building out an email strategy that’s smarter, more contextual, and more human - let’s have a conversation!

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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.