Email marketing: deliverability, segmentation and sequences
Email marketing remains the one channel where a company owns its list, while social media and advertising only rent it access. That is what makes it the channel with the lowest cost per sale when it is run well. Its performance depends on deliverability and segmentation, not on frequency or the subject line.
- An email that does not reach the inbox cannot be saved by any subject line, and you pay for the send anyway.
- Cleaning a list almost always raises sales in absolute numbers, not only rates. Paying for a smaller list is often the right trade-off.
- The welcome sequence is the only one that pays off for certain, at a one-time cost. It is also the one most often missing.
- A mistake in a send is almost never fixed by a correction email.
- An owned list is an asset on the balance sheet. An audience rented on a platform is not.
On this page
Deliverability
Deliverability is the ability of an email to reach the recipient's primary inbox rather than the spam folder or an outright rejection. It depends on the technical authentication of the sending domain, the reputation that domain has built up, and the behaviour of recipients: opens, replies, complaints and unsubscribes.
Landing in the inbox before anything else
This channel has a property no other has: the list belongs to you. An audience built on a platform can vanish with a change of rules, and you have to buy access to it again with every send. An email list stays, and its cost per sale falls as it grows. It is the only marketing asset that truly appears on your balance sheet.
If your sends have already stopped producing with no explanation, the cause is almost always technical rather than editorial. A send works like a shipment: the best product in the world is worth nothing if the parcel never arrives, and the carrier turns away shippers who pile up complaints.
Most discussions about email marketing focus on content. That is putting the cart before the horse. A perfect message that lands in the spam folder produces zero sales, and it cost the same to produce and to send.
Since the major mailbox providers tightened their requirements for volume senders, three technical elements have become non-negotiable.
Domain authentication
Three settings carry technical names and serve the same purpose: proving to mailbox providers that it really is you writing. SPF declares which servers are allowed to send on your behalf. DKIM adds a verifiable signature to every message. DMARC states what to do when a message fails the first two. Without all three, a growing share of your sends never reaches your customers, without your being warned, and you keep paying your sending platform for messages no one reads.
The complaint rate
It must stay under 0.3%. Going over degrades the domain's reputation, and that reputation takes weeks to rebuild. The most frequent cause is sending to people who do not remember signing up.
One-click unsubscribe
It must be present in the message's technical header, not only in the footer. Making unsubscribing difficult pushes recipients toward the report button. An unsubscribe costs you one contact; a complaint degrades your domain's reputation and costs you access to the entire list.
A list bought or imported without documented consent is not just ineffective: in Canada it breaches CASL, Canada's Anti-Spam Legislation, whose financial penalties are real and apply to small businesses as well.
Before deciding how to split a budget between email and the other channels, establish what a subscriber is worth to you. The method is set out in our article on the value of a subscriber.
What to check before restarting your sends
The major mailbox providers now require a complaint rate under 0.3% and a one-click unsubscribe. Beyond that, the domain's reputation degrades and takes weeks to rebuild, during which your sends no longer arrive. The risk is not losing one campaign, it is losing access to a list built over years.
- Are our three authentication settings in place, and who checked them last?
- What is our current complaint rate, and where do we look it up?
- What share of the list has opened nothing in six months, and why are we keeping it?
- Do we have documented consent for every address, and since when?
- How many sales did email produce last quarter, separately from the rest?
The answer that holds up gives a quantified complaint rate and a date of last check. A hollow answer talks about the open rate, proposes raising the frequency, or suggests buying a list.
Deciding whether to clean a list, change platforms or restart from fresh consent commits your whole channel. A 90-minute consultation settles it, with a written summary that circulates through your organization.
Segment on behaviour, not on demographics
Classic segmentation splits a list by sector, size or region. It is easy to build and weakly correlated with results. What predicts an open or a purchase is what the person did recently.
| Segment | Criterion | Treatment |
|---|---|---|
| Active | Opened in the last 90 days | Normal cadence, offers and content |
| Lukewarm | Subscribed, no open in 90 to 180 days | Reduced frequency, high-value content only |
| Dormant | No open in more than 180 days | One reactivation sequence, then removal |
| Recent customers | Purchase in the last 60 days | Onboarding support, never an acquisition follow-up |
| Unconfirmed | Sign-up without double opt-in | To remove; these are the ones that generate complaints |
Removing the dormant contacts from a list often raises the absolute number of sales, not only the rates. By improving the domain's reputation, the send reaches active recipients better. Paying for a smaller list that sells more is a trade-off that is hard to get accepted, and it is almost always the right one.
The line runs between the list and the mechanics. The list always stays in-house: the consent, your customers' data and the export must belong to you and be recoverable within an hour, whatever the provider. That is what protects you from dependence on a platform. What gets delegated is the mechanics: domain authentication, reputation monitoring, sequence building and reading the send data all require keeping watch on requirements that change several times a year. A company that owns its list and delegates its mechanics keeps the power to change providers without losing anything.
The sequences that pay off
The periodic newsletter is the most common format and the least profitable. Sequences triggered by a behaviour cost less to run and pay off more, because they are written once and arrive at the moment the person is interested in the subject. It is the only part of this channel where the effort invested keeps producing without being redone.
| Sequence | Trigger | Return |
|---|---|---|
| Welcome | Sign-up | The highest. Attention is at its peak and the cost is one-time. |
| Abandoned cart | Cart left without purchase | High in eCommerce |
| Post-purchase | Order completed | High for retention and returns |
| Reactivation | Prolonged inactivity | Medium, but protects the reputation |
| Periodic newsletter | Calendar | Low if it is not segmented |
The welcome sequence deserves a pause. It is the only moment when the person has actively asked to receive something from you, and remembers it. Three messages spread over a week, delivering what was promised and then setting out what to expect, are worth more than a lone acknowledgement of receipt. It is the highest-return project in the channel, and it is the one most often missing.
Subject, sender name and preview text
These three elements form a whole, and the order of importance often surprises. They cost nothing to change, which makes them the first place to look before investing elsewhere.
The sender name comes first. It is what decides whether the message is opened, more than the subject line. A recognizable person's name systematically beats a generic company name.
The subject line comes next. Short, precise, with no promise it does not keep. Sensationalist wording earns an open and then an unsubscribe: you trade a lasting contact for a single read.
The preview text completes it. It is the line shown after the subject in most email clients. Left empty, it displays the start of the message code, often an unsubscribe notice. It is almost always neglected.
Open rates have become unreliable since some providers preload images. An open rate that climbs without clicks following means nothing. The click and the sale remain the only measures on which a budget decision can be made.
When a mistake slips into a send
Broken link, wrong first name, incorrect price. The question is not whether it will happen, but what to do when it does, and how much the reaction itself risks costing.
The decision rule comes down to one question: does the mistake prevent the recipient from getting what they expect, or does it mislead them about a commercial commitment. If so, a correction is warranted. If not, it is not.
| Mistake | Response |
|---|---|
| Spelling mistake | Do nothing. A correction draws attention to it. |
| Empty personalization field | Do nothing. Fix the template for next time. |
| Broken link to the offer | Resend to the non-clicker segment, different subject |
| Incorrect price or date | Quick correction, and honour the announced price if the margin allows |
| Sent to the wrong segment | Do nothing unless the content is confidential |
Email is the only channel where you own your audience. All the others rent it to you, and the rent keeps rising.
Falia analysis gridA check before your next send
Automating the sequences and connecting them to the sales system are covered on the conversion rate optimization page for the measurement side, and in the goal below for full execution.
The threshold beyond which a sequence wears the list out is quantified in automated email sequences.
This point sits inside the plan described in splitting the budget across channels.
Email is a lever of the Optimize the profitability of your digital campaigns goal.
Already running a marketing team? See how we plug in as reinforcement on conversion rate optimization.
Frequently asked questions about email marketing
Why do my emails land in spam?
The most frequent causes are incomplete domain authentication, a complaint rate that is too high, or sending to contacts who do not remember signing up. SPF, DKIM and DMARC must be configured before any other optimization.
How often should you send a newsletter?
Frequency matters less than relevance. A segmented monthly send generally produces more than an undifferentiated weekly one. The right gauge is the unsubscribe rate: if it rises, the frequency exceeds the perceived value.
Should you clean your contact list?
Yes, regularly. Removing contacts inactive for more than six months improves the sending domain's reputation, which makes the following sends arrive better. The absolute number of sales often rises after a cleaning.
Which sequence should you set up first?
The welcome sequence, without hesitation. It is the only moment when the person has actively asked to receive something from you and remembers it. Three messages over a week are worth more than a simple acknowledgement of receipt.
What should you do if a mistake slips into a send?
A correction is only justified if the mistake prevents getting what was promised or misleads about a commercial commitment. A spelling mistake or an empty personalization field deserves no second send.
Is the open rate still reliable?
No, not really anymore. Some providers preload images, which triggers an open count with no real reading. The click rate and conversion remain the only solid measures for judging a send.
- Google, Email sender guidelines, accessed July 2026.
- Google Postmaster Tools, monitoring a sending domain's reputation, accessed July 2026.
- Government of Canada, Canada's Anti-Spam Legislation (CASL), accessed July 2026.
Gabriel almost always takes your first call and carries out your audit. He builds the strategy starting from your growth goal: where to put your budget, which market to test and how to connect each lead to a real sale in your CRM. He mainly leads engagements for three goals: Optimize the profitability of your digital campaigns, Develop a new market, and Generate demand and growth. With Geneviève, he also works on organic search (SEO), AI visibility (GEO) and conversion rate optimization (CRO). The sales a Google Ads or Meta Ads campaign brings in depend on the page that receives the click. He writes mainly about marketing strategy, paid advertising and measurement.
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