Email Deliverability Checklist for E-commerce

Use addresses like orders@yourdomain and vendors@yourdomain to isolate traffic and apply routing rules per stream. Segmentation limits blast radius during peak sales and simplifies parsing heuristics by context.

Update MX for each inbound subdomain and use low TTLs during rollout to enable quick rollback. Validate acceptance via SMTP tests and confirm TLS before switching production traffic.

Set p=quarantine or p=none while observing rua reports to identify vendor forwarders and misaligned senders. Use relaxed alignment if legitimate vendor systems do not sign with your domain and tune policies over time.

Ensure order emails you send are authenticated so customer and vendor replies are not filtered before reaching your inbound address. Align the 5322.From domain and set Reply-To to the correct inbound mailbox for threading.

Publish an MTA-STS policy so sending MTAs prefer TLS when delivering invoices and confirmations. This reduces downgrade issues and improves deliverability from security-conscious vendors.

Adopt formats like orders+ORD-12345@yourdomain or ORD-12345@orders.yourdomain to mint unique addresses per order. This enables deterministic routing and fraud isolation on a per-order basis.

Create a unique address when an order is placed or a vendor is onboarded and store it alongside the order record. This ensures replies and invoices map unambiguously to the correct entity.

Map orders@ to an order webhook, returns@ to an RMA webhook, and vendors@ to an AP webhook. Keep endpoints isolated so parsing changes for one stream do not affect others.

Decode quoted-printable and base64 parts, convert to UTF-8, and select the best body part for machine reading. Many vendor ERPs still emit ISO-8859-1 or Shift_JIS, which must be normalized to avoid parsing errors.

Parse patterns like [Order #12345], PO-12345, or RMA-9876 and read In-Reply-To or References to correlate with generated Message-IDs. Fail fast to a manual review queue if IDs are missing or ambiguous.

Autodetect CSV delimiters, sanitize XLSX formulas, and apply PDF text extraction or OCR for scans. Enforce size limits and mime-type validation to prevent overconsumption and unsafe content.

Store the original message for 30-90 days with a reference on the parsed record. This supports dispute resolution, parser upgrades, and legal discovery without asking vendors to resend.

Require HMAC verification on every delivery and rotate keys on a schedule or when staff changes. Add IP allowlists where possible and reject unsigned requests at the edge.

Include a stable message or event ID and enforce a dedupe window in downstream consumers. This prevents duplicate refunds or double inventory updates during retries.

Retry transient 5xx failures with jitter and push permanently failed events to a dead letter queue for manual triage. Expose tooling to replay DLQ items after fixes.

Map parsed messages into domain events like order_confirmed, invoice_received, and return_requested with JSON schema validation. Version payloads and enforce contract tests with consuming services.

Store large attachments and pass pre-signed URLs in webhook payloads to keep event sizes small. This reduces time-to-webhook and prevents downstream timeouts.

Strip or tokenize phone numbers, emails, and masked PANs from body text and attachments unless a consumer requires them. Log redaction actions with a trace ID for audits.

Collect and anonymize invoices, confirmations, and ASN notices from top partners to drive tests. Tag each sample by vendor, locale, and attachment type to improve coverage.

Validate extractors for order, PO, and RMA IDs and track false positives and negatives by vendor. Keep separate patterns for exchanges and returns to avoid misrouting.

Test CSV delimiters and encodings, Excel date formats, and PDFs with embedded fonts or images. Enable OCR fallback for scanned packing slips so line items are not lost.

Feed in vacation replies and SMTP bounces to confirm they route to a low-priority queue and do not trigger business logic. Enforce one auto-reply per thread to prevent loops.

Ensure ORD-123 and ord-123 map to the same order and that plus-address tags are parsed even with vendor rewrites. Reject tags that do not match your order ID pattern.

Replay Black Friday level volumes and measure p95 time-to-webhook and parse error rates. Pre-scale consumers and verify autoscaling policies before promotions.

Track SMTP 4xx and 5xx rates, TLS handshake errors, and queue times from receipt to webhook. Alert on sustained degradations that threaten order SLAs.

Propagate a correlation ID from SMTP receipt through parsing and webhook delivery and tie it to the order or vendor ID. This accelerates incident triage and refund investigations.

Identify new vendor relays, misaligned SPF/DKIM, and spoofing attempts against your commerce domains. Adjust alignment or vendor guidance before messages get rejected.

Track known-good vendor domains and expected sending IPs and quarantine mail when they suddenly change. Proactively request SPF updates when partners switch providers.

Apply content and header checks, enforce DKIM where required, and send unknown vendors to a review queue. This reduces phishing risk against finance and returns workflows.

Document steps for webhook outages, storage failures, or vendor send failures and include a fallback REST polling plan. Train on-call staff and keep contacts updated for vendor escalations.