Why do my emails go to spam?

Some of why your emails go to spam is on you. Some of it isn’t. This guide walks through both, so you know what to fix, what to keep an eye on, and what’s simply outside your control.

How spam filters actually decide

Before fixing anything, it helps to know roughly how the major mailbox providers (Gmail, Outlook, Apple Mail, Yahoo) decide where an email lands.

Four things go into the decision, in rough order of weight:

Proof it’s really you sending. The mailbox provider wants to confirm your business is actually behind the email, not someone pretending to be you. You handle this by authenticating your domain (more on that below).
Your sender reputation. Your sending address builds up a track record over time. Steady, low-complaint sending earns trust. Sudden spikes and complaints damage it.
What recipients do with your emails. Does this particular person open, click, reply, move your emails out of spam, or delete without reading? It’s one of the strongest factors today, and it’s specific to each recipient.
The email’s content. The provider’s filters read your subject and body and compare them against what spam typically looks like. You can’t see the rules, but you can avoid the obvious patterns.

The first two are largely on you to set up. The third you influence over time. The fourth you can nudge but never fully control.

What you can fix (highest impact)

Authenticate your sending domain

This is the single biggest thing. The major mailbox providers now require senders to prove the email really came from your business, or they spam-folder it or reject it outright, no matter how good the content is.

Authentication isn’t difficult and it’s a one-time setup. You add a few small settings where your domain is registered so mailbox providers can confirm the email really came from you. After that, you don’t think about it again.

Follow the step-by-step guide to authenticating your domain (SPF, DKIM, and DMARC).

If you only have a gmail.com or hotmail.com address

You cannot authenticate gmail.com, hotmail.com, yahoo.com, or similar free providers, because you don’t own their DNS. Sending bulk email from a personal Gmail address through any third-party tool is the most common reason small-business emails go straight to spam.

Minutemailer solves this by automatically creating a ready-made sending address for every new account. If you don’t have your own domain, use that address instead. You can rename it under your account’s email settings.

Use a real list

The fastest way to ruin your sender reputation is to email people who didn’t ask to hear from you.

Don’t buy lists. Ever. Even if the seller claims the addresses are opted in.
Don’t email old contacts who haven’t heard from you in years. An address that signed up in 2020 and never engaged is functionally a stranger today.
Watch your hard bounce rate. Minutemailer automatically moves hard-bouncing addresses to an exclusion list, so you don’t have to remove them yourself. A consistently high bounce rate still tells you something about where your contacts came from.
Retire chronically inactive subscribers. Someone who hasn’t opened anything in 12 months is dragging your sender reputation down.

The honest version: a clean list of 200 is worth more than a stale list of 2,000. Start with building a list the right way.

Pick a sensible “From” address

A personal name@business.com reads as more trustworthy than noreply@business.com. Don’t change it often. Each new sending address starts with no reputation.

Send to people who actually want it

Engagement is now a deliverability signal in its own right. If your subscribers open, click, and occasionally reply, the mailbox provider learns that your emails belong in the inbox. If most subscribers ignore or delete you without opening, the provider learns the opposite.

This means the cure for “my emails go to spam” is sometimes “send less, to fewer people, with more relevance” rather than “send more to try harder.”

What helps but takes time

A few things move slowly:

Sender reputation. Steady sending at a consistent volume earns trust month over month. A brand-new sending domain has no reputation at all, and the first few sends may underperform until the picture builds up.
Spreading large sends. When you send to thousands of contacts at once, you create a spike that filters notice. Minutemailer can spread large mailings over up to 24 hours automatically. Choose the spread option on the Test & send screen for any send over about 1,000 contacts.

Content patterns worth avoiding

Filters look at the words and structure of your email. None of these are guaranteed to spam-trigger on their own, but they make you look like a typical spammer.

ALL CAPS, especially in the subject line.
Excessive punctuation!!!!
Classic spammy phrases (“CLICK HERE NOW”, “limited time offer”, over-use of “free”, “prize”, “buy now”).
An email that’s only a single image, with no text. Always pair images with real text and include alt text.
Misleading subject lines, fake Re: or Fwd: prefixes, hashbusting tricks like “F.r.e.e.”
Links to sketchy domains, link shorteners, or any URL the filter doesn’t recognize as reputable.

These tricks worked a decade ago. Today they actively hurt you. Concentrate on writing emails that sound like a person, not a marketer trying to game an algorithm.

What you can’t really fix

A guide that pretends every deliverability problem has a solution is lying to you. Here’s the honest list:

A single recipient marked you as spam. Their personal inbox routing for you is broken from that point on. Future emails to that specific person will likely keep landing in spam, and there’s no clean way to undo it.
Corporate spam filters. If your subscriber works at a company using Mimecast, Proofpoint, or a strict internal IT policy, the rules are invisible to you and not appealable.
Mailbox provider algorithm changes. Gmail, Outlook, and the others adjust their scoring without warning. A campaign that delivered well in March might underperform in May for reasons no one outside the provider can see.
Shared servers. On smaller plans, your emails go out through infrastructure shared with other senders. If one of them behaves badly, your delivery can be temporarily affected. Established providers manage this well, but it’s never zero risk.
Personal blocklists and learned behavior. If a recipient always deletes your emails without opening, their provider eventually learns to filter you. There’s no way to manually override that.

The realistic goal isn’t 100% inbox placement. Nobody achieves that. Aim for good average delivery: most of your engaged subscribers receiving most of your emails most of the time.

How to know if it’s working

You don’t need fancy tools. Watch these signals in Minutemailer’s delivery statistics after each send.

Hard bounce rate. If hard bounces creep above a few percent, you have a list-quality problem. Minutemailer parks the addresses for you, but think about where they came from.
Soft bounces. A few are normal. A sudden spike often points at a temporary mailbox provider issue or a content concern.
Open trends over time. Don’t judge by one send. If opens drop steadily over a quarter, your list is going stale or your sender reputation is slipping.

Before any important send, send the same email to yourself at addresses on Gmail, Outlook, and Apple Mail (or iCloud). If one of them lands in spam while the others don’t, you’ve narrowed the problem to that provider’s view of you. One catch: don’t send the test to the same address you’re sending from. Some mail servers treat that as suspicious and dump it into spam on principle, which makes the test misleading.

If you suspect a broader delivery problem, see the delivery problems guide for what to check next. And if your authentication is in question, the authenticate guide walks through verifying every record. Permission and consent rules sit in the GDPR for newsletters guide.

Start with the basics

Authenticate your domain. Use a list of people who asked for your emails. Write like a person. Watch your bounce rate. Send consistently.

Do those five things and your delivery will be in the top tier of small-business senders, which is already better than most of your competition manages. The rest is patience, because reputation takes time to build, and the honesty that some bounces and spam placements you simply can’t fix.