Here's the uncomfortable truth of email marketing: the best flow in the world, written by the best copywriter in the world, is worth zero if it lands in spam. Deliverability is your emails' ability to reach your customers' primary inbox, and it's the floor everything else stands on. The trap is that it's invisible. Your platform says "sent", everything looks normal, and meanwhile part of your list has stopped seeing you. You're paying for ads to acquire customers your own email can no longer reach.
What changed: the inbox providers raised the bar
Since February 2024, Gmail and Yahoo hold bulk senders to requirements that used to be "best practices": domain authentication (SPF, DKIM, DMARC), one-click unsubscribe, and a spam complaint rate kept under 0.3%. Below those standards, your sends get filtered, period. Deliverability is no longer an expert topic: it's a prerequisite.
The three pillars of sender reputation
Inbox providers judge every sender on three things:
- Technical authentication. SPF, DKIM and DMARC prove the email really comes from you. Without them, you look like a fraudster.
- Engagement. Opens, clicks, replies. A list that ignores your sends tells providers your emails interest no one.
- Negative signals. Complaints, bounces, mass unsubscribes. Each one outweighs ten opens.
Everything in the plan below works on one of these three pillars.
The 12-step plan
1. Diagnose before touching anything. An inbox placement test (specialized tools like GlockApps do this) tells you where your sends actually land at Gmail, Outlook and the rest: primary inbox, promotions or spam. Without that starting point, you're flying blind.
2. Open your platform's deliverability dashboard. Klaviyo and the serious platforms show delivery rates, bounces, complaints and trends. Look at it weekly, not once a year, and act on the recommendations it surfaces.
3. Set up a dedicated sending domain. Sending from your platform's shared domain means sharing the reputation of thousands of strangers. A branded sending domain isolates your reputation and puts it under your control.
4. Verify SPF, DKIM and DMARC. The first two usually come with the dedicated sending domain setup. DMARC is done at your DNS provider: start in monitoring mode (p=none with a reporting address), then tighten toward quarantine once the reports come back clean. It's an hour of work that protects everything downstream.
5. Clean your list. Remove bounces, invalid addresses and dead profiles. Every inactive address you keep costs money (platforms bill per profile) and dilutes your engagement metrics. A smaller list that opens beats a big list that sleeps.
6. Send to the engaged, not to everyone. Build an "engaged" segment sized to your sending frequency: the more often you send, the shorter the engagement window should be. And maintain a "do not send" list: unsubscribes, bounces, complaints, and recent buyers already inside your post-purchase sequences.
7. Vary and refresh your content. The same templates, the same phrasing and the same links repeated for months end up looking like spam, to the filters and to the humans. Rotate the angles: product education, behind the scenes, social proof, offers.
8. Use your platform's native blocks. Real buttons and real text rather than one big sliced image. An all-image email is a classic spam signal, and it's unreadable when images don't load.
9. Mix in plain-text emails. A share of your sends in plain or near-plain text (around one send in five) clears the filters more easily and creates a closeness that heavily designed templates don't have. It's also the natural format for a personal note from the founder.
10. Invite replies. A reply from your customer is the strongest engagement signal there is: it effectively whitelists your address in their mailbox. Ask real questions in your welcome and post-purchase emails, and answer them.
11. Increase volume gradually. A domain that jumps from 500 to 20,000 sends overnight sets off the alarms. Ramp up in stages while watching complaints and bounces at each step. Sending more isn't the problem: sending more all at once is.
12. Turn on a sunset flow. The flow that re-engages the unengaged one last time, then removes them from the active list. It's the step everyone postpones because it shrinks the subscriber counter, and it's the one that protects everything else. The full sequence is in our flow catalog.
A word on compliance here
In Quebec, CASL (Canada's anti-spam legislation) requires valid consent before any commercial send and a working unsubscribe handled promptly, and Law 25 governs the personal information in your list. Good news: everything above pulls in the same direction as the law. A consenting, engaged list is both compliant and deliverable. And never buy a list: it's illegal here, and it's the shortest path to a blacklist.
Where to start this week
If you only do three things: run a placement test (step 1), verify your authentication (steps 3-4), and build your engaged segment (step 6). Those three fix the majority of situations we see in our email audits.
FAQ
How do I know if my emails are landing in spam? Three signals: an open rate sliding for no reason, an inbox placement test confirming it, and your platform's deliverability dashboard showing complaints or bounces climbing. The placement test is the only one that gives you the direct answer, provider by provider.
What are SPF, DKIM and DMARC, in one sentence each? SPF lists the servers allowed to send for your domain; DKIM signs each email to prove it wasn't altered; DMARC tells providers what to do with an email that fails the first two, and sends you reports.
Won't deleting subscribers hurt my sales? No: a subscriber who hasn't opened in months already wasn't buying. By keeping them, you pay for their profile and degrade the reputation that decides whether your REAL customers receive your emails. The sunset flow gives them one genuine last chance before removal.
Want an email program that lands in the primary inbox and sells? Book a call