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Why your emails go to spam (and how to fix it)

By Andrej Uzusienis · July 24, 2026 · 7 min read

Few things are more frustrating than a well-written email that never gets seen because it landed in spam. Filtering is not random - it comes down to a handful of signals. Here are the real reasons, and how to fix each.

1. Missing or broken authentication

If your domain has no SPF, DKIM or DMARC, providers treat you with suspicion. This is the most common and most fixable cause - see our guide to SPF, DKIM and DMARC.

2. A poor sender reputation

Mailbox providers score your domain and IP based on past behaviour: complaints, bounces, and how people engage. A few bad sends can dent it for weeks. New domains have no reputation at all, which is why they need warming up.

3. Sending to bad addresses

High bounce rates and hitting spam traps are among the fastest ways to get filtered. If your list is old or was scraped, clean it first - our list hygiene checklist walks through it.

4. Content that looks like spam

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5. Low engagement

Providers watch whether people open, reply and move your mail out of spam. If most recipients ignore you, your placement gets worse. Send to people who actually want your email, and prune the ones who never engage.

The fix, in order

  1. Set up SPF, DKIM and DMARC.
  2. Verify and clean your list.
  3. Warm up new domains slowly.
  4. Write like a human and include an unsubscribe link.
  5. Remove chronically unengaged contacts.

Work through these and inbox placement almost always recovers.

Spotted an error in this article? Email hello@mailcheq.com and we will fix it.