Ingestion
Store SMTP emails, SMS, HTTP dumps, and other payloads from 16 services.
Each time an email, SMS message, or webhook payload is received by Sinkbox, it counts towards your monthly ingestion limit. The limit resets at the beginning of each calendar month.
Stored items remain in your inbox until purged or cleaned up by your project's retention policy.
Ingestion limits & protocol matrix
Compare message volume and protocol support across plans.
| Feature / Protocol | Free | Starter | Pro | Business |
|---|---|---|---|---|
| Monthly Ingestion Volume | 50 / mo | 2,000 / mo | 10,000 / mo | 100,000 / mo |
| Email: SMTP | ✓ Included | ✓ Included | ✓ Included | ✓ Included |
| Email: Generic API | ✓ Included | ✓ Included | ✓ Included | ✓ Included |
| Email: Drop-in | ✕ | ✓ Included | ✓ Included | ✓ Included |
| Email: Manual paste / EML | ✓ Included | ✓ Included | ✓ Included | ✓ Included |
| SMS: Generic API | ✕ | ✓ Included | ✓ Included | ✓ Included |
| SMS: Drop-in | ✕ | ✓ Included | ✓ Included | ✓ Included |
| HTTP Dump/Webhook | ✕ | ✓ Included | ✓ Included | ✓ Included |
| Push: Drop-in | ✕ | ✕ | ✓ Included | ✓ Included |
| Voice: Drop-in | ✕ | ✕ | ✓ Included | ✓ Included |
| Chat: Drop-in | ✕ | ✕ | ✓ Included | ✓ Included |
Custom enterprise plans include custom volume scaling up to 10M+ events/month.
SMTP Ingestion
Capture outbound emails from frameworks and servers via standard SMTP. Point your app host to smtp.sinkbox.dev on port 2525 with your project credentials.
Manual Email / EML Ingestion
Paste raw MIME messages or EML files directly from your email client into your Sinkbox inbox. This allows you to test real production emails, inspect headers, preview HTML renderings across clients, and run compatibility audits. Each manually imported email counts as 1 item towards your monthly quota and is included on all plans.
SMS API Ingestion
Capture simulated SMS and OTP 2FA text messages via drop-in API compatibility for Twilio and 46elks.
HTTP Request Dumps
Capture full HTTP request dumps from any webhook or client, with headers, query parameters, JWT authentication decoding, and body parsing.
Drop-in Service Endpoints
Drop-in endpoints let you replace a real third-party API with Sinkbox during development and testing. Simply point your SDK or HTTP client at your Sinkbox base URL and all outgoing messages are silently captured in your inbox instead of being delivered.
Each drop-in URL embeds your Sinkbox project credentials directly in the path:
POST
https://ingest.sinkbox.dev/dropin/{username}/{key}/{service}/{version}/{type}The {username} and {key} segments are the credentials from your project API key. No additional authentication headers are required.
Supported Services & Endpoints
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| Service | Endpoint path | SDK / env override |
|---|---|---|
| Resend | /dropin/{user}/{key}/resend/v1/email |
RESEND_API_URL |
| SendGrid | /dropin/{user}/{key}/sendgrid/v3/email |
SENDGRID_API_URL |
| Twilio SMS | /dropin/{user}/{key}/twilio/2010-04-01/sms |
TWILIO_API_URL |
| Twilio WhatsApp | /dropin/{user}/{key}/twilio/2010-04-01/whatsapp |
TWILIO_API_URL |
| Twilio Voice | /dropin/{user}/{key}/twilio/2010-04-01/voice |
TWILIO_API_URL |
| 46elks SMS | /dropin/{user}/{key}/46elks/a1/sms |
Base URL override |
| 46elks Voice | /dropin/{user}/{key}/46elks/a1/voice |
Base URL override |
| FCM (Firebase) | /dropin/{user}/{key}/fcm/v1/push |
Base URL override |
| APNs (Apple) | /dropin/{user}/{key}/apns/v1/push |
Base URL override |
| OneSignal | /dropin/{user}/{key}/onesignal/v1/push |
Base URL override |
| Slack webhook | /dropin/{user}/{key}/slack/v1/webhook |
Webhook URL override |
| MS Teams webhook | /dropin/{user}/{key}/teams/v1/webhook |
Webhook URL override |
| Discord webhook | /dropin/{user}/{key}/discord/v1/webhook |
Webhook URL override |
API Key Permissions
Access to each ingestion service and drop-in endpoint can be selectively granted or revoked per API key. For full details on setting up permissions and using our testing APIs, see the API & Automation documentation.