Email Parsing API Checklist for SaaS Platforms

Define a stable top-level schema with a version field so you can evolve fields like bodies, attachments, and authentication results without breaking consumers.

Segment raw MIME storage, parsed records, queues, and metrics by tenant to prevent data leakage and to enable per-tenant quotas and analytics.

Prefer webhooks for latency and scale, keep a REST inbox for recovery and reprocessing, and document how to fall back during consumer outages.

Use Message-ID plus SMTP identifiers and a hash of the canonicalized MIME to suppress duplicates and to safely retry deliveries.

Decide how long to keep raw messages vs. extracted fields, and provide tenant-level controls that satisfy audit and privacy requirements.

Enumerate concrete flows like support tickets, billing replies, and lead capture, then specify what fields and attachments each feature needs.

Require TLS for inbound MX and webhook egress, enforce HMAC signatures, rotate secrets, and restrict console access with SSO and MFA.

Issue subdomain or alias-based addresses (e.g., tenant.feature@yourdomain) to simplify routing and to enable tenant-level throttling.

Parse recipient tags like support+case-123@ and subdomains like case-123@tenant.yourdomain to encode metadata for downstream handlers.

Run authentication checks and include pass or fail results in the parsed JSON so downstream systems can apply trust policies.

Resolve catch-alls, distribution lists, and forwarded addresses to a canonical tenant and feature using a directory or routing table.

Detect common auto-response patterns and set a standardized event type so product logic can avoid creating duplicate tickets or leads.

Set X-Loop or custom headers, rate limit per conversation, and detect your own system addresses to stop recursive processing.

Apply size thresholds and sender reputation checks, route risky items to a review queue, and expose quarantine status in APIs.

Handle Base64, quoted-printable, and legacy charsets so text is readable and safe, and record the decoded encoding in metadata.

Prefer text/plain when present, otherwise convert HTML to sanitized text and keep both versions for downstream choice.

Extract Message-ID, In-Reply-To, and References to attach emails to existing objects like tickets or threads in your SaaS.

Capture filename, media type, size, and a secure URL, scan for malware, and block or redact disallowed types per tenant policy.

Apply heuristics or ML to remove disclaimers and previous messages, and allow per-tenant rules to tune behavior by language.

Map content-id attachments to their HTML references, host them securely, and keep a traceable link to the original part.

Store a whitelisted set of raw RFC 5322 headers like Received and Authentication-Results to support compliance and forensics.

Include a payload version header and top-level event type so consumers can route logic and future changes do not break clients.

Compute HMAC over body plus timestamp, require clock skew checks, rotate secrets, and publish verification examples in multiple languages.

Retry non-2xx responses with exponential backoff, cap attempts, and move exhausted events to a dead letter queue with requeue tools.

Include a unique delivery ID and advise consumers to de-dupe on that key so at-least-once delivery does not create duplicates.

Provide list and get APIs with filters by tenant, date, status, and event type, plus secure pre-signed URLs for large attachments.

Let developers send sample events, replay failed attempts, and configure per-tenant transforms like field masking before delivery.

Publish an OpenAPI spec, clear error codes with remediation steps, and provide lightweight SDKs that verify signatures out of the box.

Include different charsets, nested multiparts, calendar invites, S/MIME, and long threads so parsers handle real-world variability.

Generate malformed headers and bodies to ensure the parser fails safely, logs clearly, and never crashes worker processes.

Track queue depth, parse latency, webhook success rate, attachment size distribution, and alert on anomalies by tenant.

Attach a message and delivery ID to every log line and span so you can trace a single email from MX to webhook consumer.

Encrypt raw MIME and attachments with KMS, use bucket policies for tenant isolation, and set lifecycle rules to control costs.

Scale parser and delivery workers based on queue metrics, apply per-tenant quotas, and shed load gracefully under spikes.

Practice recovery for webhook outages, antivirus latency, and storage failures with documented steps and on-call checklists.