A campaign that lands in spam earns nothing. Before you spend another hour on design or copy, spend thirty minutes on deliverability, because it decides whether any of that work gets seen.

To improve email deliverability you do not need a consultant. You need a handful of habits that keep inbox providers trusting you, plus the Gmail and Yahoo sender rules that became mandatory in 2024. This guide covers both.

Why deliverability decides whether your emails get seen

Deliverability is the share of your emails that reach the inbox instead of the spam folder. It is not a switch you flip once. Inbox providers like Gmail and Yahoo watch how people react to your emails and adjust how much of your mail they trust.

Send to people who open and click, and your reputation climbs. Send to a stale list that ignores you, and the filters start routing you to spam for everyone, including the buyers who want your emails. Deliverability sits underneath your whole program, so it is the first piece of the DTC email marketing fundamentals to get right. Everything below protects it.

How to improve email deliverability

Three habits move deliverability the most, and the Gmail and Yahoo rules set the floor under them.

Balance text and images in every email

Gmail reads the ratio of images to text. An email that is one big image with a thin line of text looks like spam to the filter, whatever it looks like to you. Give every email real text it can read.

Your footer is the easiest place to fix this. Company details, a plain unsubscribe line, shipping or contact info - useful text that adds weight without cluttering the design. Build it once into your master template, and every send inherits a healthier text-to-image balance with no extra work.

Clean your list on a schedule

Nothing drags deliverability down faster than mailing people who never open. After 60 to 90 days of no opens or clicks, a subscriber is telling Gmail your mail is not worth reading, and Gmail listens.

Set up a re-engagement email for those quiet subscribers. If they still do not open, suppress them. Watching your subscriber count drop stings, but a smaller list that engages beats a big one that ignores you. The engaged list is what protects inbox placement for everyone still on it.

Authenticate your sending domain

Authentication proves an email really came from you. Three DNS records do it: SPF, DKIM, and DMARC. Think of them as your email's ID card. Without it, you look suspicious to every inbox provider. In Klaviyo, setting up a dedicated sending domain configures all three for you.

Get this right once and it pays off on every send. It also stops other people from spoofing your domain, which can wreck a reputation you spent months building.

What Gmail and Yahoo now require

In February 2024, Gmail and Yahoo made the biggest deliverability change in years. If you send to 5,000 or more addresses a day, three things stopped being optional:

• Authenticate with SPF, DKIM, and DMARC. The section above covers how.

• Offer one-click unsubscribe in the email header, and honor it within a couple of days.

• Keep your spam complaint rate under 0.3%, and ideally under 0.1%.

That last number is the one most brands miss. If more than three in a thousand recipients mark you as spam, Gmail can start rejecting your mail before it reaches a folder. In the accounts we manage, we track that complaint rate every month against a 0.02% target, far under the 0.3% ceiling, because trouble shows up there long before Gmail acts on it. The fix is the same as the habits above: mail people who want to hear from you, make unsubscribing easy, and keep the list clean. The full requirements live in Google's sender guidelines and Yahoo's sender best practices.

A healthy sender reputation is also what lets the rest of your program work. Your core Klaviyo flows only earn if they reach the inbox, and the same is true of every campaign you send.

Email deliverability FAQ

What is a good email deliverability rate?

Aim for 95% or more of your sends reaching the inbox. The number that matters more is your spam complaint rate: keep it under 0.3%, and under 0.1% is the safe target. Watch both in Google Postmaster Tools, which shows how Gmail actually sees your domain rather than what your sending platform reports.

Why are my emails going to spam?

Usually one of three things: you are mailing people who stopped engaging, your emails are mostly image with little text, or your domain is not authenticated. Work through all three. If you send in bulk, also confirm you meet the Gmail and Yahoo sender rules, since missing those can route you to spam on their own.

How do I authenticate my email domain?

Set up SPF, DKIM, and DMARC records for your sending domain. In Klaviyo, adding a dedicated sending domain configures all three in a guided setup. If you send from Klaviyo or Shopify, follow their dedicated-domain instructions rather than editing DNS records by hand.

How often should I clean my email list?

Review engagement every month and suppress subscribers with no opens or clicks in 60 to 90 days, after one re-engagement attempt. A list that decays quietly is the most common hidden cause of falling open rates.

The bottom line

Deliverability is not a mystery. Balance text and images, clean your list on a schedule, authenticate your domain, and stay inside the Gmail and Yahoo rules. Do those four and your open rates climb, because your emails actually arrive.

Start with the one you have skipped longest. For most stores that is list cleaning, and it also feeds your welcome flow a healthier audience. If you would rather hand the whole system to people who run it daily, talk to us about your account.