Mailchimp Emails Going to Spam? Here's Why (and How to Fix It)

April 18, 2026 • InboxGreenEmail Team

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You're sending through Mailchimp, your open rates used to be decent, but now emails are going to spam — or nobody's opening at all.

Using Mailchimp doesn't protect you from spam filters. If your domain's DNS records aren't set up correctly, Mailchimp emails will fail authentication and get filtered.

Here's exactly why Mailchimp emails go to spam and how to fix it.

1. You haven't authenticated your domain in Mailchimp

By default, Mailchimp sends on behalf of your domain using its own servers. Without domain authentication, your emails show "via mcsv.net" in Gmail's headers — a red flag for spam filters.

To fix this, you need to add two things to your domain's DNS:

  • SPF: Add include:servers.mcsv.net to your SPF record
  • DKIM: Add the CNAME records Mailchimp gives you (found under Account → Domains → Authenticate)

After adding these, run a check at InboxGreen.email/check to confirm they're live and aligned.

2. Your SPF record is over the 10-lookup limit

SPF records can only trigger 10 DNS lookups. Many businesses add multiple include: statements over time — one for Mailchimp, one for Google Workspace, one for their CRM — and eventually hit the limit.

When SPF hits the lookup limit, it returns PermError, which fails just like a missing SPF record. This causes DMARC failures and emails going to spam.

Check if you're over the limit using the free SPF Lookup or SPF Generator tools.

3. Your DMARC policy is too strict (or missing)

DMARC connects your SPF and DKIM. If DMARC is missing, some mail providers won't know how to handle authentication failures. If your policy is set to p=reject but your Mailchimp DNS isn't configured, every email gets rejected.

The right sequence:

  1. Set up SPF + DKIM for Mailchimp first
  2. Add DMARC at p=none to start monitoring
  3. Only move to p=quarantine or p=reject once you see clean reports

Generate a safe DMARC record with the free DMARC Generator.

4. Your list has too many stale or invalid addresses

Mailchimp has automatic list cleaning, but it can't catch everything. Sending to addresses that haven't opened in 12+ months hurts your sender reputation — even if those addresses technically exist.

Google and Yahoo's 2024 sender requirements made this worse: high spam complaint rates (above 0.1%) now trigger active filtering.

Clean your list before your next campaign: remove anyone who hasn't opened in 6–12 months, and immediately remove hard bounces.

5. Your "From" domain doesn't match the authenticated domain

DMARC alignment requires that your "From" address domain matches the domain used in SPF or DKIM. If you're sending from [email protected] but Mailchimp is authenticating under a different domain or subdomain, DMARC fails.

This is especially common if you use a free email address (Gmail or Yahoo) as your From address. Gmail and Yahoo now block bulk mail sent from their domains via third-party services. Use your own domain.

Quick diagnostic checklist

  1. Check your domain at InboxGreen.email/check — look for SPF, DKIM, and DMARC results
  2. In Mailchimp: Account → Domains → check if your domain shows "Authenticated"
  3. Send a test to a Gmail account you control, open "Show original", read the Authentication-Results line
  4. Check for blacklisting using the Blacklist Checker
  5. Check your complaint rate in Google Postmaster Tools (free, register at postmaster.google.com)

If SPF passes, DKIM passes, and DMARC shows dmarc=pass — but emails are still going to spam — the problem is list quality or sending reputation, not authentication.

For a personalized fix guide with copy-paste DNS records for your exact Mailchimp setup, try the InboxGreen FixKit.

Free Deliverability Scan

Check SPF, DKIM, DMARC and List-Unsubscribe for your domain in seconds.