Introduction
Mailchimp is one of the most common SaaS senders on a typical DMARC rollout sender list. Out of the box, it signs with mailchimp.com — which doesn't align with your domain. Enabling custom DKIM aligns it.
Why this topic matters
A typical SMB sending newsletter via Mailchimp will see DMARC failures from this sender until custom DKIM is configured. Five minutes of work; durable alignment.
How to enable custom DKIM in Mailchimp
- Mailchimp admin → Account → Settings → Verified domains.
- Add your domain.
- Mailchimp generates DKIM records for your domain.
- Publish the CNAME in your DNS.
- Verify in Mailchimp; signing starts.
SPF setup
Optionally add Mailchimp's SPF include:
“text v=spf1 include:_spf.google.com include:servers.mcsv.net -all “
Watch SPF lookup budget.
Step-by-step approach
- Enable custom DKIM as above.
- Confirm signing with a test campaign sent to a Gmail address.
- Watch DMARC reports for Mailchimp sender pass rate.
- Pair with SPF best practices.
Best practices
- Use Mailchimp's custom DKIM, not default.
- Test before tightening DMARC policy.
- Document the selector in your runbook.
- Pair with proper list hygiene for deliverability.
- Re-verify after any Mailchimp account changes.
Recommended next step
If Mailchimp is in your sender estate, enable custom DKIM today. Five minutes of work.
FAQ
Does custom DKIM affect Mailchimp deliverability?
Positively. Authenticated mail has better placement.
Can I rotate Mailchimp DKIM keys?
Yes — Mailchimp supports rotation. How to rotate DKIM keys safely.
What about Mailchimp Mandrill?
Mandrill is Mailchimp's transactional product. Same custom DKIM pattern.
Will switching break campaigns in progress?
No, if you keep both old (default) and new (custom) DKIM live during transition.
Does this work with Mailchimp's "via mailchimpapp.com" branding?
Custom DKIM removes the "via" notation. Cleaner sender appearance.
Final thoughts
Mailchimp + DMARC is one of the easiest sender configurations. Enable custom DKIM, publish the CNAME, verify. Done.