Segmentation
Email MarketingAlso: Audience Segmentation · Email Segmentation · Customer Segmentation
Quick definition
Segmentation is the practice of dividing your audience into smaller groups based on shared characteristics, so you can send more relevant messages to each group. Segments can be built from demographic data, purchase history, email engagement, website behaviour or any combination of the above.
How it varies across Australia
Across the Australian businesses we review, segmentation is one of the most unevenly adopted email practices. Many have the data to segment but send to the full list by default. The gap between what the data allows and what gets used is usually large.
See email marketing performance across Australian industries →The four main types
Groups based on who the person is: location, industry, job title, age bracket.
Groups based on what the person has done: purchases, pages visited, emails opened.
Groups based on where the person is in their relationship with you: new, active, lapsed, churned.
Groups based on signals of what the person wants next: browsed a category, downloaded a guide, requested a quote.
What it actually means
Most email lists are treated like a single audience. Everyone gets the same message on the same day. That approach made more sense when email platforms were basic. It makes less sense now that most platforms can split a list by almost any attribute in seconds.
Segmentation is the discipline of deciding which groups inside your audience deserve different messages. The logic is simple: a customer who bought last week needs different communication than one who hasn't opened anything in eight months. A prospect who read three pricing pages is not in the same place as one who signed up for a newsletter and went quiet.
Good segmentation doesn't require a data science team. It requires clear answers to two questions: what do I know about each person, and what difference should that make to what I send them?
The answer to those two questions produces your segments. Everything else, the platform configuration, the content variations, the send logic, is execution against the answer.
Sending the same email to everyone isn't email marketing. It's email broadcasting.
How it shows up
Segmentation shows up in your email platform as audience filters, tags, lists or properties that determine who receives each send. It shows up in your CRM as contact fields that drive automation rules. It shows up in your paid media accounts as custom audiences built from customer data.
The signal that segmentation is working is diverging performance between segments. If your re-engagement segment opens at a different rate than your active segment, the segments are real. If performance is identical across every segment you've defined, the segments aren't meaningful or the messages aren't different enough to matter.
The Australian context
Australian privacy law, specifically the Privacy Act and Australian Spam Act requirements enforced by ACMA, adds a layer that pure segmentation decisions can't ignore. You can only send marketing emails to people who have consented to receive them, and that consent has to be traceable. Segmentation strategies that rely on inferred intent or third-party data lists can create compliance problems that outweigh the engagement gains.
First-party segmentation, built from your own data with clear consent, is both the safest and usually the most useful approach. Australian audiences are also smaller than US equivalents, which means segment sizes drop quickly when you layer multiple criteria. A segment with fewer than a few hundred contacts usually needs a different content approach than a broadcast to thousands.
Where people get this wrong
Related terms
Common questions
How many segments should I have?
Start with the fewest segments that reflect genuinely different audience needs. For most businesses, three to five meaningful segments outperform ten loosely-defined ones. Add segments when you have evidence that a new split would change what you'd say, not just because the data exists.
What's the difference between segmentation and personalisation?
Segmentation divides your audience into groups that receive different messages. Personalisation customises the message for each individual. Segmentation usually comes first, personalisation layers on top. Both require the same foundation: knowing something meaningful about your audience.
Can I segment without a CRM?
Most email platforms have basic segmentation built in, so a full CRM isn't a hard requirement. You can segment on engagement signals alone, like who opened the last five emails, who clicked a specific link, who hasn't engaged in 90 days. Start there if your data infrastructure is still developing.
Does segmentation affect deliverability?
Yes, positively. Sending to engaged segments rather than your full list improves your sender reputation because a higher share of recipients open and interact. Continued sending to large disengaged segments drags deliverability down over time. Suppressing unengaged contacts is both a segmentation decision and a deliverability one.
Keep exploring
About New Rebellion
New Rebellion is a marketing intelligence consultancy. We build tools, score Australian businesses on how their marketing actually performs, and publish Debrief every day. This dictionary is part of how we work in the open.
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