Email Infrastructure Checklist for Financial Services

List exact mailboxes used for invoices, statements, chargebacks, and regulatory notices, and enumerate trusted sender domains (banks, processors, auditors). This tight scope reduces fraud and simplifies routing rules.

Assign data classes for PANs, account numbers, SSNs, and transaction records per mailbox with masking rules. Classification drives encryption, parsing access, and downstream redaction policies.

Define retention for raw MIME, parsed JSON, and attachments, and implement immutable logs for access and edits. Ensure legal hold workflows can suspend deletion for investigations.

Map where emails and parsed data are stored and replicated, and enforce TLS in transit plus AES-256 at rest. Align controls with FFIEC, PCI DSS, and local bank secrecy rules.

Review SOC 2, PCI attestation, penetration tests, and breach history of relay providers and inbound email APIs. Add contractual controls for notification, uptime SLAs, and data handling.

Define recovery point and time objectives covering MX acceptance, queues, parsers, and webhooks. Run failover drills to secondary relays and regions to verify objectives.

Use separate subdomains (e.g., invoices.bank.example) to isolate routing policies and security posture. This reduces blast radius and clarifies sender expectations.

Set MX priorities to direct mail to the primary SMTP relay and keep a tested secondary relay warmed with health checks. Avoid cold standby to prevent acceptance gaps.

Validate that partner messages pass SPF and DKIM with aligned domains, and set DMARC at least to quarantine with daily reports. This blocks spoofing that targets finance workflows.

Publish MTA-STS policy to require TLS with trusted CAs and use TLS-RPT to detect downgrade attempts. Financial artifacts must never traverse plaintext links.

Calibrate limits to absorb batch invoice sends while blocking floods. Only permit known IP ranges from processors and correspondent banks to minimize abuse.

Cap message size and restrict attachments to approved financial formats (PDF, CSV, XLSX, EDI). Return clear bounce reasons with secure alternative submission paths.

Expose intake endpoints behind a gateway that inspects headers, rate limits, and blocks known bad patterns. Use allowlists for webhook receivers and parser control planes.

Support decryption for counterparties who encrypt financial payloads, storing keys in HSMs or KMS. Audit key access and rotate on a defined schedule.

Scan at acceptance and prior to parsing to catch weaponized PDFs, macros, and link-based threats. Quarantine suspicious messages and notify senders securely.

Store credentials in a vault, rotate on a cadence, and enforce least-privilege scopes for inbound API tokens. Tie rotations to automation with alerting on drift.

Use RBAC to separate dev, test, and prod mailboxes and limit who can view raw PII. Keep audit logs on every read, parse, redaction, and export event.

Require HMAC or asymmetric signatures on delivery POSTs, enforce strict time windows, and track nonce usage to block message replays.

Parse MIME into structured JSON, preserving boundaries, content types, and encoding. Support nested attachments, inline images, and text fallbacks for reliability.

Use field-level models tuned to financial document layouts, track confidence per field, and set thresholds for auto-accept versus manual review.

Normalize vendor-variant fields like line totals, tax, and PO references to a consistent schema. Auto-apply GL codes and cost center mappings for posting.

Generate content hashes of attachments and track message-IDs to prevent double payment and duplicate postings. Expose idempotency in webhook deliveries.

Normalize to ISO 4217 currency codes, locale-safe number parsing, and UTC timestamps. Record source formats for audit and reconciliation.

Automatically create cases for low-confidence fields, validation failures, or policy violations. Capture reviewer decisions and feedback to retrain parsers.

Retry transient failures with capped backoff and isolate permanently failing events to DLQs. Keep event ordering where required for accounting workflows.

Use time-based or ID cursors to fetch new messages reliably without duplication. Throttle clients and apply per-tenant quotas to maintain fairness.

Generate test messages that cover common bank and vendor layouts, edge cases, and corrupt MIME. Validate MX acceptance, parsing, and webhook delivery paths.

Track 4xx/5xx by sender, time, and relay, and measure field-level extraction accuracy against targets. Surface trends to engineering and compliance.

Wire alerts to on-call rotations when domain alignment breaks, webhook signatures fail, or scanners detect threats. Include rich context for fast triage.

Store original MIME alongside normalized JSON for a defined period, with immutable checksums and chain-of-custody logs. This supports dispute resolution and audits.