Why your store's emails go to spam (and what to fix before Black Friday)

Online store emails go to spam mainly for three reasons: contacts who no longer read them, an unauthenticated domain and too many spam complaints compared with Gmail's and Yahoo's thresholds. Fix it in this order: authentication, one-click unsubscribe, excluding inactive contacts, volume that grows step by step. Often nobody notices for weeks. The platform says "delivered" while part of the list no longer sees anything. Below you'll find the signals to read in your data, what mailbox providers have required since 2024 and what to fix before the end of November.

Why do my marketing emails go to spam, and how do I improve deliverability?

Because your customer's mailbox provider decides every time where the message goes. Gmail, Outlook or Yahoo look mainly at two things: whether the sender really is who it claims to be, and how recipients behave with its emails. If the domain isn't authenticated, if many people delete without opening, if someone hits "report spam", the sender's reputation drops. The next emails land in spam or get rejected.

You improve deliverability by working on those two fronts: prove your identity with SPF, DKIM and DMARC, and write only to people who want to read you. Subject lines, images and copy matter, but they come later.

Delivery and inbox placement are not the same thing

Delivery is the recipient's server accepting the email. Inbox placement (deliverability) is that email's ability to reach the inbox instead of the spam folder. A campaign can show close to 100% delivered and still land in spam for part of the list. For your sending platform, in both cases the message was "delivered".

When delivery fails, it's called a bounce:

• Soft bounce: a temporary rejection. Full mailbox, server unreachable at that moment, message too large. The platform usually retries.
• Hard bounce: a permanent rejection. The address doesn't exist, the domain is invalid, or the server decided to block you. Don't contact that address again.

Every platform has its own rules for suppressing contacts that keep soft bouncing. Check the ones in the tool you use.

Why poor inbox placement skews your data

If some recipients get your email in spam, opens drop and it looks like the subject line isn't working. The same goes for A/B tests: if one variant lands in spam more than the other, the test measures the filter, not the copy. Before drawing conclusions about subject lines, send times or offers, rule out a deliverability problem first.

There's also the opposite effect. With Mail Privacy Protection, Apple downloads the remote content of received emails in the background, whether the recipient opens them or not. Many platforms record that download as an open. So your overall open rate can look healthy even when half your list on Gmail no longer sees anything. Clicks and orders are more reliable signals.

The most common causes

1. Contacts who no longer read. Subscribers from years ago who don't remember signing up, contacts imported from an old system. They don't open, they delete, sometimes they report you.
2. Disproportionate frequency. Going from one newsletter a week to one a day, to the whole list, without separating engaged contacts from everyone else.
3. Subject lines that don't keep their promise. A discount announced in the subject that isn't in the email, a fake "Re:", a false "your order is on hold". People who feel tricked don't look for the unsubscribe link. They hit "spam".
4. A hard-to-use unsubscribe. A tiny gray link, mandatory questions, a login required. The "report spam" button is always easier.
5. An unauthenticated or misconfigured domain. Sending from the platform's shared domain, no DMARC record, an SPF record that doesn't include every service sending email on your behalf.
6. Invalid addresses. Typos collected at checkout, abandoned mailboxes, spam traps that ended up on your list. Lots of hard bounces tell the provider your list isn't maintained.

What Gmail, Yahoo and Outlook require

Since 2024, the three most used providers have put in writing what they expect from high-volume senders. You hit Gmail's threshold sooner than you'd think. An example: a store with 24,000 subscribers, half of them on Gmail, sends a newsletter to everyone and delivers 12,000 emails to Gmail in one day, more than twice the limit.

The consequences are real. Since November 2025, Gmail has enforced these checks more strictly: non-compliant messages can be rejected, temporarily or permanently, or sent to spam. Outlook rejects emails that fail the required authentication, with an error message to the sender, instead of moving them to the junk folder.

Abandoned cart emails count toward these numbers. They are marketing emails and need an unsubscribe option just like newsletters. We cover this in are abandoned cart emails transactional or marketing?.

How to tell if your emails are going to spam

No provider warns you. You figure it out by cross-checking a few signals.

• Opens and clicks collapsing on a single provider. Break down results by recipient domain. If your Gmail click rate drops from, say, 2.5% to 0.6% in two weeks while on Outlook and Yahoo it holds steady, you have an inbox placement problem on Gmail, not a subject line problem.
• Bounces broken down by reason. Full mailboxes and temporarily unavailable servers are normal. Rejections that mention reputation, policy or authentication need attention right away, especially if they cluster on one provider. They're the sign that provider no longer trusts your domain.
• Rising spam complaints. Look at them over several weeks, not campaign by campaign.
• Google Postmaster Tools. It's free and, for emails sent to Gmail addresses, it shows spam rate, reputation, authentication and delivery errors. You set it up by verifying your domain with a DNS record.
• A seed test. Before an important send, you email test addresses on different providers and check where it lands. It's a useful snapshot, not your actual reputation.

Don't take the deliverability score literally

Many platforms show a health score based on the last 30 days that combines opens, clicks, bounces, unsubscribes and complaints. It's useful, but it also drops for harmless reasons. A win-back campaign to inactive contacts will always have low opens. A sunset flow that asks "do you still want to hear from us?" pushes unsubscribes up, and that's exactly its job. A campaign sent an hour ago hasn't collected opens yet. A drop you can explain with a choice you made isn't an alarm. An unexplained drop, together with reputation bounces on one provider, is.

What to fix, in order

1. Authentication. Send from your own domain, ideally a dedicated subdomain such as news.yourstore.com, with SPF, DKIM and DMARC. If you have no DMARC record, start with p=none and reports turned on, and move to stricter policies once you're sure every service sending on your behalf is authenticated.
2. One-click unsubscribe. The platform handles the technical header. Your job is to check that it's active and that there's a readable link at the bottom of the email. A preference center ("fewer emails", "new arrivals only") can sit next to the unsubscribe option, never replace it.
3. Excluding inactive contacts. Remove from regular sends anyone who hasn't opened or clicked for a period that matches your purchase cycle. For a coffee bean store where customers reorder every month, four months of silence is a lot. For a furniture store, a full year can be normal.
4. Periodic cleaning, checked by hand. Automated sunset flows help, but if they run on their own you don't know who they're removing or how many. A review every two or three months works better: you identify the segment, send two or three win-back emails with a real reason (something new, a useful guide, your best sellers), then a last email that clearly asks whether the person wants to stay, with two equally visible buttons. Anyone who doesn't respond gets suppressed. Hard bounces and contacts who never opted in leave the list. It's the same logic Google describes: ask for confirmation periodically and consider unsubscribing people who don't read.
5. Volume that grows gradually. Google recommends avoiding sudden spikes if you don't have a history of large sends. If you need to scale up, do it step by step, starting with your most engaged segments.
6. Content that matches the subject line. The subject promises what's inside, the sender name is recognizable, and the email isn't a single image with no text.

This also applies to automated messages produced with external tools. Recovery emails generated by a service like AchillesAI, for example, go out from the store's own email account: the reputation stays the store's, and writing different copy for each customer avoids sending the exact same message in bulk. Timing and flow structure are explained in how to set up an abandoned cart flow in Klaviyo.

The Black Friday case

At the end of November almost every store ramps up sending at the same time, and a domain with a fragile reputation gives way right on the days that matter. Black Friday 2026 is Friday, November 27, so the work needs to be spread over the weeks before.

The full plan, with the waitlist, segments and a day-by-day sequence, is in Black Friday emails: the four-week plan.