There are many reasons that mailbox providers could flag your email as spam.
Here are the most common reasons we see and how to fix them!
If your emails are landing in spam, it usually means something about the email—or how it was sent—tripped spam filters. Here’s a breakdown of common reasons and what you can do about them:
🔐 1. Authentication Issues
Email services look for certain authentication protocols to trust that your email really came from you:
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SPF (Sender Policy Framework) – tells mail servers which IPs are allowed to send for your domain.
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DKIM (DomainKeys Identified Mail) – signs your emails to verify they haven’t been altered.
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DMARC (Domain-based Message Authentication, Reporting, and Conformance) – tells receiving servers how to handle SPF/DKIM failures.
👉 Fix: Check if SPF, DKIM, and DMARC are properly set up for your domain using tools like MxToolbox or Mail Tester.
📛 2. Your Email Looks “Spammy”
Spam filters scan content for red flags. Some common issues:
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Too many images and not enough text
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Use of ALL CAPS, excessive exclamation marks!!!, or spammy phrases like “FREE,” “ACT NOW,” etc.
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Poor HTML formatting or mismatched tags
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Broken links or shady-looking URLs
👉 Fix: Write emails that are clean, personalized, and natural. Keep a good balance of text and images.
📬 3. You're Using a “Dirty” Sending Address or IP
If your domain or the IP address of your sending server has a bad reputation (like being on a blacklist), your emails can get flagged.
👉 Fix: Use reputation tools like Sender Score or check blacklists on MxToolbox.
📉 4. Low Engagement
If people often delete your emails without opening, or mark them as spam, providers like Gmail and Outlook will take that as a bad signal.
👉 Fix:
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Clean your list: remove inactive or unengaged users.
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Segment your audience and send relevant content.
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Ask recipients to whitelist your email.
⚙️ 5. You're Sending from a Free Email Address
If you're sending mass emails from Gmail, Yahoo, etc. (like yourname@gmail.com), it often gets filtered.
👉 Fix: Use a custom domain (like you@yourdomain.com) and a reputable email marketing platform (e.g. Mailchimp, ConvertKit, Brevo).