Technical
Why your order confirmation emails are landing in spam, and nobody in the company knows
Richard K. · September 25, 2026 · 9 min read
A customer places an order, gets no confirmation email, and assumes the order failed. They email support, or worse, they place a second order on a competitor's site while waiting to hear back. Nobody on your team did anything wrong that day. A DNS record just quietly stopped working, and every transactional email since then, order confirmations, shipping updates, password resets, has been landing in spam folders or vanishing entirely.
This is one of the more insidious failure modes in ecommerce because it produces no error message. Your store's checkout works. Your email service reports messages as sent. Nothing in your admin panel turns red. The only signal is a slow rise in "where's my order" tickets, and by the time someone connects the dots, it might have been happening for weeks.
What SPF, DKIM, and DMARC actually do
Email authentication exists because anyone can put anything in the "From" field of an email. Without a way to verify sender identity, spam filters would have no basis for trust, so a set of DNS-based standards developed to fill that gap.
SPF (Sender Policy Framework) lists which mail servers are allowed to send email on behalf of your domain. If your order confirmations come from Shopify's mail servers or a third-party sender like Klaviyo or Mailchimp, your SPF record needs to explicitly authorize them.
DKIM (DomainKeys Identified Mail) attaches a cryptographic signature to outgoing mail, letting the receiving server verify the message wasn't altered in transit and genuinely came from a domain that holds the matching private key.
DMARC (Domain-based Message Authentication, Reporting and Conformance) tells receiving mail servers what to do when a message fails SPF or DKIM checks, reject it, quarantine it (usually meaning spam), or let it through anyway. DMARC also gives you a reporting mechanism so you can see who is sending mail claiming to be you.
When all three are configured correctly, mail providers like Gmail and Outlook treat your transactional email as trustworthy. When one of them breaks, quietly, without any alert to you, the same providers start treating your order confirmations as suspicious. For background on the mechanics, Google's own guidance for bulk email senders is a useful reference, as is Shopify's documentation on email domain authentication.
How this breaks without anyone touching it
The frustrating part of SPF/DKIM/DMARC failures is that they rarely result from someone making an obvious mistake. They usually result from someone making a reasonable change somewhere else.
A common scenario: you add a new email marketing app to send abandoned cart sequences or review requests. The app asks you to add a CNAME or TXT record for DKIM. If your SPF record already lists multiple senders and you exceed ten DNS lookups (a hard limit in the SPF specification), the entire SPF check silently fails for every sender on the record, not just the new one.
Another common trigger: migrating from WooCommerce to a new host, or moving your domain's DNS to a new registrar. If SPF, DKIM, and DMARC records aren't copied over exactly, mail sent through your old configuration stops authenticating on day one at the new host.
A third: your DMARC policy gets tightened (often by an IT consultant trying to improve security) from "none" to "quarantine" or "reject," without confirming that every legitimate sending service, your storefront platform, your marketing tool, your helpdesk, is properly authenticated first. The policy change is correct in principle. The execution takes down mail that was working the day before.
In each case, the store owner discovers the problem only when someone complains, which mirrors other silent breakages we've covered, like the abandoned cart email that never sends or webhook failures that never reach your admin. The common thread is that the system reports success internally while the customer-facing outcome fails externally.
Your mail server saying 'sent' and a customer's inbox saying 'received' are two different claims, and nothing in most store dashboards checks whether the second one is true.
The support ticket pattern that should worry you
Because this failure is gradual and inconsistent, it doesn't always announce itself as a spike. Gmail, Outlook, and Yahoo each run their own spam filtering logic, so a broken DMARC record might send 80% of Gmail recipients' confirmations to spam while only affecting 20% of Outlook recipients. That inconsistency is exactly what makes it hard to diagnose from ticket volume alone.
Watch for a cluster of tickets that all say some version of "I never got my confirmation" or "is my order real?" spread across different customers, different order values, and different times of day. If it were a one-off glitch, you'd expect it to be rare and random. If it's authentication, you'll see it recur steadily, week after week, until someone fixes the DNS.
A useful habit borrowed from general operational hygiene: during your regular store health check, send yourself a real test order and confirm the email lands in your primary inbox, not spam, and check the message headers for "pass" results on SPF and DKIM. Doing this once a month costs a few minutes and catches drift before it compounds.
How to check and fix your authentication records
You don't need to be technical to run a basic diagnostic. Free tools like MXToolbox or Google's own Postmaster Tools will check your domain's SPF, DKIM, and DMARC records and flag syntax errors, exceeded lookup limits, or missing entries. Run one of these checks any time you add a new email-sending tool or migrate hosting providers.
If you're on Shopify, the platform's email domain authentication walkthrough will generate the correct records for you to add at your registrar. WooCommerce stores typically rely on whatever transactional email plugin or SMTP service is configured (an app like WP Mail SMTP, or a service like SendGrid or Postmark), and each of those provides its own DNS setup instructions, which is worth checking directly on woocommerce.com or the provider's own documentation. BigCommerce stores using a third-party email or marketing app should confirm the app's sending domain is included in SPF and has a valid DKIM selector published.
Once you've confirmed the records are correct, don't treat it as a one-time fix. DNS records can be altered by a hosting migration, a registrar transfer, or a well-meaning contractor cleaning up unused entries, the same way an expired SSL certificate or a lapsed domain renewal can undo a working setup without anyone intending it. Ongoing email deliverability monitoring, checking authentication status and inbox placement on a schedule rather than only when a customer complains, is the difference between catching this in a day and catching it in a month.
Frequently asked questions
- How do I know if my order confirmation emails are going to spam?
- The clearest signal is a pattern of customer tickets asking whether their order went through, clustered around the same time period rather than isolated incidents. You can confirm it directly by placing a test order yourself using a Gmail or Outlook address you don't normally check, then looking in the spam folder and examining the message's raw headers for SPF, DKIM, and DMARC results. A "fail" or "softfail" result on any of the three points to an authentication problem rather than a content-based spam trigger.
- Can adding a new email marketing app break my existing transactional emails?
- Yes, adding a new sending service is one of the most common triggers for this failure because SPF records have a hard limit of ten DNS lookups, and each additional authorized sender can push an existing record over that limit. When the limit is exceeded, the entire SPF check fails, not just for the new sender, which can silently degrade deliverability for order confirmations that were working fine before. Always run a fresh SPF and DKIM check after connecting any new email or marketing integration.
- Do Shopify, WooCommerce, and BigCommerce handle email authentication automatically?
- None of the three platforms fully manage this for you without some setup on your part, particularly once you add third-party senders. Shopify provides a domain authentication feature that generates the correct DNS records, but you must add them at your registrar and re-verify after any DNS migration. WooCommerce and BigCommerce depend on whichever SMTP service or email app you connect, and each requires its own SPF and DKIM entries, so the responsibility for keeping records current sits with the store owner regardless of platform.
The takeaway
Transactional email deliverability is one of those systems that works perfectly, silently, for months, until a single DNS change breaks it just as silently. Nobody sees an error. No dashboard turns red. The only trace is a slow accumulation of confused customers and support tickets that, taken individually, look like isolated incidents.
The fix isn't complicated once you know where to look: verify SPF, DKIM, and DMARC whenever you change email senders, hosting, or DNS providers, and check inbox placement periodically rather than assuming a "sent" status means "delivered." Cassian™ includes checks designed to catch this kind of silent operational drift across your store, feeding into the overall Cassian Score™ so a slipping signal shows up before it becomes a pile of tickets, not after.