You spent time crafting the perfect email, hit send… and crickets. No replies, no engagement—just a bunch of emails that never made it to the inbox.

If your emails are going to spam in 2025, it’s not random. Spam filters have evolved, and inbox providers (like Gmail and Outlook) use sophisticated AI to determine which emails get through.

Let’s break down the most impactful reasons your emails are getting flagged—and how you can fix it.

1. You Have a Bad Sender Reputation (Most Important Factor)

Spam filters are obsessed with your sender reputation. This is the single biggest factor determining whether your email lands in the inbox or the junk folder.

What Hurts Your Reputation?

• ❌ Low engagement: If people aren't opening, clicking, or replying to your emails, inbox providers assume they don’t want them.

• ❌ Spam complaints: If too many people mark your email as spam, that’s a one-way ticket to the junk folder.

• ❌ High bounce rates: If you’re sending emails to bad addresses, it signals that you’re not managing your list properly.

• ❌ Past spammy behavior: If you’ve sent poorly targeted or bulk emails in the past with low engagement, it hurts your domain reputation.
  
  

How to Fix It

• ✅ Only send emails to engaged, opted-in recipients.

• ✅ Make your emails interesting and valuable so people actually open them.

• ✅ Keep your email list clean—remove inactive subscribers and invalid addresses.

• ✅ Avoid cold outreach from domains you want to protect. Use a separate domain if necessary.
  
  

2. You’re Not Properly Authenticated (SPF, DKIM, DMARC)

This is the technical stuff—but it’s crucial. Email providers use authentication records (SPF, DKIM, DMARC) to verify that your emails are legit. If these aren't set up correctly, your emails might never even make it to the inbox.

What Happens Without Authentication?

• ❌ Your emails look suspicious and get filtered as spam.

• ❌ Hackers could impersonate your domain, leading to phishing attacks.

• ❌ Email providers (like Gmail) don’t trust your messages, leading to poor deliverability.
  
  

How to Fix It

• ✅ Set up SPF and DKIM records in your DNS settings (your email provider will have guides).

• ✅ Configure DMARC for extra security (not mandatory but recommended).

• ✅ Use a dedicated sending domain for cold emails to protect your main domain.

  
  

3. Your Emails Get Marked as Spam Too Often

Every time someone clicks “Mark as Spam,” it tells email providers: Hey, this sender is annoying. Get too many spam reports, and your emails will always go to spam.

Why Do People Mark Your Emails as Spam?

• ❌ They don’t recognize you.

• ❌ They didn’t sign up for your emails.

• ❌ Your subject line was misleading.

• ❌ You’re sending too many emails.

• ❌ It’s hard to unsubscribe (more on that later).

  
  

How to Fix It

• ✅ Send emails only to people who want them.

• ✅ Make your sender name recognizable.

• ✅ Keep your messaging relevant and non-pushy.

• ✅ Make unsubscribing EASY (yes, really).
  
  

4. Your Emails Have Low Engagement

Email providers love engagement—opens, clicks, replies, and positive actions (like marking an email as “important”). If your emails get ignored, spam filters take it as a sign that nobody cares, and future emails will go straight to spam.

How to Fix It

• ✅ Write subject lines that actually make people want to open your emails.

• ✅ Keep emails short, clear, and relevant.

• ✅ Personalize your emails—it makes a huge difference.

• ✅ Encourage replies! Ask a question to prompt engagement.
  
  

5. Your Email Content Looks Spammy (Even If It’s Not)

Spam filters analyze what’s inside your email. If your content looks sketchy, your email might get flagged even if your domain is clean.

What Triggers Spam Filters?

• ❌ Spammy phrases like “Congratulations! You’ve won!” or “Get rich quick.”

• ❌ ALL CAPS or excessive exclamation points (!!!).

• ❌ Too many images with little text (looks like an advertisement).

• ❌ Poorly formatted HTML or broken links.

  
  

How to Fix It

• ✅ Keep your emails looking natural—like a real person wrote them.

• ✅ Avoid excessive capitalization and punctuation.

• ✅ Make sure your links are valid and match the displayed text.
  
  

6. You Don’t Have an Easy Unsubscribe Option

Here’s the deal: if someone wants to stop receiving your emails and can’t find an easy way to unsubscribe, they’ll do the next best thing—mark your email as spam. And that kills your deliverability.

How to Fix It

• ✅ Always include a visible “Unsubscribe” link.

• ✅ Don't hide it in tiny text at the bottom.

• ✅ Make unsubscribing easy—one click, no drama.

(And no, “Reply ‘unsubscribe’ to opt out” doesn’t count. People won’t bother—they’ll just mark you as spam.)

7. You’re Sending Too Many Emails (Volume Matters)

Even if everything else is fine, sending too many emails too quickly can still land you in spam.

What’s Too Many?

🚨 For cold emails: Stick to 100 emails per day per email address (50 is even safer).
🚨 For marketing emails: If engagement drops, dial it back.

How to Fix It

✅ Space out your emails instead of blasting all at once.
✅ Use an email warm-up tool to slowly increase sending volume.
✅ Monitor your bounce and complaint rates—high numbers mean you’re sending too much.

8. You’re Using Link Shorteners (Instant Spam Flag)

Spam filters HATE link shorteners like Bitly. Why? Because scammers use them to hide malicious links.

How to Fix It

• ✅ Always use full URLs or properly formatted hyperlinks.

• ✅ Make sure the displayed URL matches the destination URL.
  
  

9. Your Email Contains Attachments (Big No-No)

Attachments are risky. They’re often used for phishing attacks, so spam filters are extra cautious.

How to Fix It

• ✅ Instead of attachments, use a cloud link (Google Drive, Dropbox, or DocSend).

• ✅ If you must send an attachment, keep it small and use common formats like PDFs.
  
  

Final Thoughts: How to Stay Out of Spam

Spam filters in 2025 are smarter than ever. They don’t just look for obvious spam—they analyze engagement, authentication, reputation, and content to decide where your email goes.

If you’re struggling with deliverability, focus on:

• ✅ Improving engagement (opens, clicks, replies).

• ✅ Setting up SPF, DKIM, and DMARC.

• ✅ Keeping your email list clean.

• ✅ Writing natural, non-spammy content.

• ✅ Sending at a reasonable volume.
  
  

Fix these, and your emails will have a much better chance of landing where they belong—in the inbox. 🚀