Why Are My Emails Going to Spam? Understanding Email Deliverability and How to Fix It
Your email went out. The design was clean, the offer was solid, the copy was tight. And it still didn't move the needle.
Before you question the subject line or the send time, check the basics: it may never have reached the inbox.
Spam filtering has gotten more sophisticated, and the factors that trigger it go well beyond obvious red flags. Here's what's actually going on and how to fix it.
What Is the Spam Folder?
The spam folder is where email clients (Gmail, Outlook, Apple Mail, and others) automatically route messages they determine to be unsolicited, irrelevant, or potentially harmful. Spam filters use a combination of sender reputation signals, authentication checks, engagement data, and content analysis to make that determination. When your email fails enough of those checks, it doesn't reach the inbox.
How Do I Know If My Emails Are Going to Spam?
The most reliable signals are in your ESP dashboard. Watch for:
Low open rates, especially if they've dropped without an obvious explanation
High bounce rates, both hard and soft
Elevated spam complaint rates. Anything above 0.08% is worth taking seriously; above 0.1% is a problem
Low click-to-open rates. If the people who do open aren't clicking, deliverability may be filtering out your most engaged contacts
Tools like Litmus and GlockApps let you run pre-send spam tests to catch issues before they affect your sender reputation.
Why Are My Emails Going to Spam? The Most Common Causes
1. Low engagement rates
Email clients track how recipients interact with your emails: opens, clicks, moves to inbox, replies. When large portions of your list consistently ignore your emails, mailbox providers interpret that as a signal that your content isn't wanted. Over time, they start routing your sends to spam proactively, even for subscribers who might have engaged.
This is why blasting your full list with every campaign isn't just lazy strategy. It actively damages deliverability.
2. Poor email list hygiene
Sending to invalid addresses generates hard bounces. Sending to disengaged subscribers suppresses your engagement rates. Both tell mailbox providers that your list wasn't built carefully and that your emails probably shouldn't be prioritized.
Clean lists aren't just good practice. They're a deliverability requirement.
3. Missing or misconfigured authentication
SPF (Sender Policy Framework), DKIM (DomainKeys Identified Mail), and DMARC (Domain-based Message Authentication, Reporting, and Conformance) are the technical protocols that verify you are who you say you are. Without them, or with misconfigured records, mailbox providers can't confirm your emails are legitimate and will treat them accordingly.
SPF authorizes which mail servers can send on your behalf. DKIM adds a cryptographic signature to each email that verifies it hasn't been tampered with in transit. DMARC tells receiving servers what to do when either check fails and gives you reporting visibility into authentication failures across your sending domain.
If you're using a custom sending domain (which you should be), all three need to be properly configured.
4. Spam trigger language and misleading subject lines
Excessive capitalization, certain high-pressure phrases, and subject lines that don't match the content of the email are all signals spam filters are trained to catch. Beyond the filter risk, misleading subject lines damage trust and frustrated subscribers report emails as spam.
Write subject lines that accurately represent the email. Clarity outperforms cleverness, and it doesn't get you flagged.
5. Sending too frequently
High send frequency without corresponding relevance leads to fatigue. Fatigued subscribers unsubscribe, ignore, or hit the spam button, all of which hurt your sender reputation. There's no universal "right" frequency, but the question to ask is whether every email you're sending is genuinely worth the recipient's attention.
How to Fix Email Deliverability: What Actually Works
Authenticate your sending domain properly
Set up SPF, DKIM, and DMARC through your DNS provider. Your ESP, whether that's Klaviyo, Attentive, or another platform, will have documentation for this. Don't skip it, and don't set it and forget it. Check that records are current whenever you change ESPs or sending infrastructure.
Clean your list regularly
Remove hard bounces immediately. For inactive subscribers, run a re-engagement campaign before you sunset them, but sunset them if they don't respond. A smaller list of engaged contacts will always outperform a large list of disengaged ones, both for deliverability and revenue.
Segment before you send
Not every email belongs in front of your entire list. Segment by behavior, purchase history, engagement recency, and interest, then send campaigns that are actually relevant to each group. Higher relevance drives higher engagement, which improves your sender reputation over time.
Build content subscribers actually want
Deliverability is downstream of content quality. If recipients aren't engaging, spam filters eventually catch on. Personalization, clear CTAs, and a reasonable text-to-image ratio all contribute, but the bigger question is whether the email is worth opening in the first place.
Use a reputable ESP and a custom sending domain
Shared sending IPs at low-quality ESPs mean your reputation is tied to everyone else on that infrastructure. Using a platform like Klaviyo and setting up a dedicated custom sending domain gives you control over your sender reputation and separates your performance from unrelated senders.
Monitor your metrics and adjust
Deliverability isn't something you set up once. Open rates, click rates, bounce rates, and spam complaint rates all require ongoing attention. Use your ESP's reporting alongside tools like Litmus or GlockApps to run pre-send tests and catch issues before they become patterns.
Frequently Asked Questions
What spam complaint rate is too high? Google's Gmail guidelines recommend keeping spam complaint rates below 0.10%, with 0.08% as the threshold to watch. Rates approaching 0.30% put you at serious risk of widespread filtering.
Does email authentication actually prevent emails from going to spam? Yes. Missing or misconfigured SPF, DKIM, and DMARC are among the most common reasons legitimate emails get filtered. Authentication doesn't guarantee inbox placement, but without it, you're relying on mailbox providers to give you the benefit of the doubt. They often won't.
How often should I clean my email list? At minimum, review your list quarterly. Remove hard bounces immediately after any send. For inactive subscribers with no opens or clicks in 90 to 180 days, run a re-engagement campaign. If they don't re-engage, remove them.
Can sending too many emails get me blacklisted? Sending high volumes to disengaged contacts can damage your sender reputation enough to land you on a blocklist. It's not the volume alone. It's the ratio of engaged to unengaged recipients and the complaint rates that come with sending to people who don't want to hear from you.
The Bottom Line
Most deliverability problems aren't mysterious. They come from skipped authentication, unclean lists, and content that isn't earning its place in someone's inbox. Fix the fundamentals, monitor consistently, and treat every send as something worth your subscribers' attention. That's what keeps you out of spam.
If you're a D2C brand and your email program isn't pulling the revenue it should, we're happy to take a look.
