What does deliverability actually mean?
There is a gap between 'sent' and 'read,' and deliverability is the name for it. Your email tool can report a campaign as delivered while the inbox providers, the Gmails and Outlooks of the world, quietly slide it into spam. Or into a promotions pile where it is never seen. The gap is measurable: in EmailTooltester's deliverability tests across major email platforms, only 83.1 percent of marketing email landed in the inbox on average. The rest was filtered to spam or went missing entirely. Sent is your side of the story. Reached is theirs, and theirs is the only one that pays.
Here is the reassuring part: the inbox providers are not trying to block you. They are trying to protect their users from mail nobody wants, and there is a lot of it. Nearly half of all email sent worldwide is spam: 47.27 percent of global email traffic in 2024, according to security firm Kaspersky. Every habit in this guide is really the same move: proving, over and over, that your mail is wanted. Do that and you are on the same side as the gatekeeper.
Prove your store is really the sender
The first question an inbox provider asks is blunt: is this sender really who they claim to be? Spammers forge sender names constantly, so unproven mail is treated as guilty until proven innocent. Proving it is a one-time setup that tells the world's inboxes 'mail from this store is genuinely from this store.'
You do not need to understand the machinery, and you should not try to hand-build it. Your email platform and whoever manages your domain name set it up together, once, and then it simply works in the background. Think of it as the difference between a letter with your shop's real return address and letterhead, and one with no sender at all. One gets opened; the other gets binned.
Only send to people who asked
The single biggest lever on deliverability is not technical at all: only send to people who genuinely asked to hear from you. Inbox providers watch how people react to your mail. Send to someone who wanted it and they open, click, and never complain: a vote in your favor. Send to someone who did not and they ignore or report it: a vote against. Those votes decide where your next campaign lands, for everyone on your list.
This is why bought lists, scraped addresses, and 'everyone who ever checked out' are so dangerous. Even a few annoyed strangers marking you as spam teaches the provider that your mail is unwanted, and then your loyal customers stop seeing you too. A smaller list of people who chose you outperforms a big list of people who did not, every time, on every measure that matters. Asking the right way is a craft of its own: capturing email consent you can prove walks through it, form by form.
Keep the list clean
Lists decay. People change jobs, abandon old addresses, and mistype their email at checkout. Every dead or misspelled address you keep mailing is a small strike against you. A message bounces, or worse, lands in a trap address providers use to catch careless senders.
- Verify addresses as they come in, so an obvious typo is caught at the form instead of poisoning your list later.
- Let inactive addresses go. Someone who has not opened anything in a long time is dead weight. Mailing them only tells providers your mail gets ignored.
- Never re-add someone who left. An unsubscribe is a closed door; walking back through it is the fastest way to a spam complaint.
Pruning a list feels backwards. You spent effort growing it. But deliverability rewards quality, not size. A clean, engaged list is one that inbox providers learn to trust, and that trust is what carries your mail past the filter.
Write mail that behaves like wanted mail
How you write shapes where you land. Inbox filters read your mail the way a wary person would, and a few habits mark you as trustworthy rather than pushy.
- Sound like your shop, not a billboard. All-capitals subject lines, walls of exclamation marks, and 'FREE!!!' are the visual grammar of spam, and filters know it.
- Make leaving easy. A clear, one-click unsubscribe is not a loss. It sends people out the polite door instead of hitting 'report spam,' which does far more damage.
- Keep a rhythm. Long silence followed by a sudden blast reads as suspicious. A steady, expected cadence trains both your readers and the filters to expect you.
The through-line is respect. Mail that respects the reader is mail that behaves like the wanted mail it is trying to be: easy to leave, honest in the subject line, sent on a rhythm she expects.
Which signals actually matter?
You do not need a wall of metrics. A few signals tell you whether the inbox is staying open, and all of them are early warnings you can act on before real damage is done.
| Signal | What it's telling you |
|---|---|
| Bounces | Mail returning undelivered means dead or wrong addresses. Clean them out before they cost you. |
| Spam complaints | Even a trickle is loud. It means some of these people did not really want your mail; find out who and why. |
| Opens and clicks trending down | Fading engagement is the slow leak that sinks deliverability: a sign to prune and re-earn attention, not to send harder. |
| Sudden silence from one provider | If opens from Gmail or Outlook fall off a cliff, you may be landing in their spam folder specifically. Slow down and check. |
The operator's checklist
The whole guide, as the list you can act on this week:
- Confirm your sender is proven: ask your email platform or domain host whether SPF, DKIM, and DMARC are set up for your sending.
- Send only to people who genuinely asked. No bought lists, no scraped addresses, no 'everyone who ever checked out.'
- Verify addresses at the form, and let dead and inactive ones go instead of mailing them forever.
- Write like your shop, not a billboard, and make leaving a one-click affair.
- Keep a steady, expected sending rhythm rather than rare sudden blasts.
- Watch bounces, complaints, and engagement, and treat the first dip as a prompt to prune, not to push harder.
Where Overvio fits
Most of deliverability is habit, and the habits above hold whatever tool you use. Where Overvio helps is in making the right habit the easy one. Email marketing built for e-commerce handles the sender proof for you as part of setup, verifies addresses as they arrive, and keeps a one-click unsubscribe on every message without you thinking about it.
Because Overvio connects directly to your WooCommerce store, it also knows who actually bought and who actually engaged, so it can help you keep the list to people who want to hear from you, which is the habit that carries the most weight of all. Good deliverability is not a trick you buy; it is a discipline the right tool makes hard to get wrong.