Why are my marketing emails going to spam?
Marketing emails land in spam for mechanical reasons: missing SPF, DKIM or DMARC records, a stale list, or a spammer-like sending pattern. How to fix each.
Legitimate emails from real businesses get treated as spam messages for mechanical reasons. Usually it is one of three things: your domain is not properly authenticated (the SPF, DKIM and DMARC records that prove the email is really from you), your list is stale or bought so people report you, or your sending pattern looks like a spammer’s. Since 2024 Google and Yahoo enforce these rules formally, and most of the fixes are free and quick.
Few things are more dispiriting than spending an afternoon on a proper email to your customers and discovering half of them never saw it. The good news is that modern spam filters are not mysterious. They run on a short list of checks, and once you know which one you are failing, the fix is usually mechanical.
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How the spam filter actually decides
Every mailbox provider – Gmail, Yahoo, Outlook – scores your email on roughly the same three things.
Authentication. Can the receiver prove the email genuinely came from your domain? This is checked through three small records in your domain’s DNS settings: SPF (which servers may send for you), DKIM (a digital signature on each message) and DMARC (instructions for what to do when the first two fail). If these are missing or wrong, you look exactly like a fraudster pretending to be you.
Reputation. What have recipients done with your previous emails? Opened and replied, or deleted unread and hit “report spam”? Providers track this per sending domain. Enough complaints and everything you send starts landing in the junk email folder, even for people who want it.
Engagement. Do people actually read what you send? Email recipients who ignore you month after month tell the filter your mail is unwanted, and it starts sending you to the spam folder by default.
Content and subject lines matter less than folklore suggests. The word “free” in a subject line, or pushy sales language generally, will not doom a well-authenticated email to a clean list. But authentication and reputation problems will doom even the most carefully written one.
The 2024 rule change that caught people out
In February 2024, Google and Yahoo turned best practice into enforced requirements for anyone sending to their users. These rules apply to legitimate emails from real businesses, not just spammers. Every sender must have SPF or DKIM set up and keep their reported spam rate below 0.3% in Google’s Postmaster Tools. Senders of more than 5,000 messages a day – which includes plenty of modest businesses with big customer lists – must have SPF, DKIM and DMARC all in place, offer one-click unsubscribe, and include a working unsubscribe link in every marketing email.
The practical effect: since 2024, a missing DNS record does not just risk the spam folder, it can get your email rejected outright. If your deliverability fell off a cliff in the last couple of years, this is the first place to look.
The three usual causes, and their fixes
| Cause | The tell-tale sign | The fix |
|---|---|---|
| Authentication records missing or broken | Test emails to a Gmail address land in spam; your email platform shows warnings about domain verification | Add or repair the SPF, DKIM and DMARC records in your domain’s DNS. Your email platform’s setup guide gives the exact values |
| List problems: bought, scraped or stale | Low opens from the start, complaints, addresses that bounce | Delete non-openers ruthlessly, never buy a list, only email people who asked to hear from you |
| Sending pattern | Long silences then sudden big campaigns, or identical blasts to everyone | Send smaller, regular emails; start by re-warming your most engaged customers |
Check your authentication first (it is the most common fault)
This is the fix that solves the majority of small business deliverability problems, and it is also the most neglected, because it lives in DNS settings most owners never touch.
Log into your email platform (Mailchimp, Klaviyo, HubSpot, your newsletter tool) and look for “domain authentication” or “sender verification” in the settings. Every reputable platform shows whether your domain is verified and gives you the exact SPF and DKIM records to add. Adding them means pasting two or three short values into your domain’s DNS panel, wherever your domain is registered. DMARC is one more record in the same place; even the basic “p=none” monitoring policy counts towards the requirement.
If this sounds technical, it is genuinely a twenty-minute job for whoever looks after your website, and it only needs doing once. It is also the single highest-value twenty minutes in email marketing.
Then look honestly at the list
Bought and scraped lists are the second great cause, and no clever sending fixes them. People who never asked for your email report it, and a complaint rate above 0.3% actively damages delivery to everyone else, including your real customers. The same applies, more slowly, to old lists: addresses from years ago bounce, get abandoned, or get turned into spam traps.
The discipline is simple: only email people who chose to hear from you, and remove the ones who stop opening. A list of 800 people who read beats 8,000 who do not, on every measure that matters, including whether you reach the inbox at all. If you are still building, how to build an email list for your small business covers the clean way to grow one, from signup form to welcome message.
How to test where you stand
Two free checks tell you most of what you need. First, set up Google Postmaster Tools for your domain: it shows your spam rate and domain reputation as Gmail sees them, and it is the same 0.3% line Google enforces. Second, before your next campaign, send it to a Gmail address you control and see where it lands. If it hits spam there, it is hitting spam for your customers.
One caution: do not test by asking ten friends to rescue your email from their spam folders and mark it “not spam”. Individual rescues feel productive but do not repair a domain reputation. The records and the list quality do that.
The bottom line
Emails land in spam for boring, fixable reasons: missing authentication records, a list that does not want the mail, or an erratic sending pattern. Set up SPF, DKIM and DMARC once, keep the list to people who asked, send regularly, and watch your spam rate in Postmaster Tools. Do those and the inbox takes care of itself, which means the time you spend writing is finally worth something. For what to put in the emails once they arrive, see what a small business should actually send to its list.
Frequently asked questions
Is it true that certain words send you to spam?
Largely a myth left over from twenty years ago. Modern filters weigh authentication and reputation far more than vocabulary. A properly authenticated email to an engaged list survives “free”, “offer” and “sale” in subject lines perfectly well. Obsessing over trigger words while your DKIM record is missing is rearranging deckchairs.
How do I find out my spam complaint rate?
Google Postmaster Tools, free, once you verify your domain. It shows your spam rate and reputation as Gmail sees them. Google’s own requirement is to keep the reported rate below 0.3%.
Can I email a list I bought or inherited?
A bought list is the fastest route to the spam folder: those people never asked for your email and a share will report it, damaging delivery to your genuine customers too. An inherited list is usable only if the subscribers genuinely opted in for your emails and know who you are. When in doubt, re-ask permission with a one-off confirmation email and keep only the people who say yes.
I fixed the records. How long until delivery recovers?
Authentication fixes can improve placement within days. Reputation takes longer, because it is rebuilt from recipient behaviour over weeks: send first to your most engaged customers, keep volumes steady, and let the good signals accumulate. Expect weeks, not months, if the underlying problems are actually fixed.
Does my email platform handle all this for me?
Partly. The platform sends with good infrastructure and provides the exact DNS records you need, but it cannot add those records to your domain or clean your list for you. The authentication settings and list hygiene are the owner’s side of the bargain.
Sources and checks
- Google, Email sender guidelines (authentication, 5,000-per-day requirements, spam rate below 0.3%, one-click unsubscribe), checked 4 November 2026: https://support.google.com/a/answer/81126
- Yahoo Sender Hub, Sender best practices (SPF/DKIM minimum, DMARC, spam rate below 0.3%, list-unsubscribe), checked 4 November 2026: https://senders.yahooinc.com/best-practices/
- Bamsh Knowledge Centre: How do I build an email list for my small business? https://bamsh.co.uk/how-do-i-build-an-email-list-for-my-small-business/
- Bamsh Knowledge Centre: What should a small business actually send to its email list? https://bamsh.co.uk/what-should-a-small-business-actually-send-to-its-email-list/
- Bamsh Knowledge Centre: Is email marketing worth it for a small business? https://bamsh.co.uk/is-email-marketing-worth-it-for-a-small-business/
Sources checked 4 November 2026. Emails land in spam for boring, fixable reasons; fix the records, the list and the sending pattern, and the inbox takes care of itself.
