What is SparkPost Relay Webhooks?
SparkPost Relay Webhooks is the inbound email processing feature of the SparkPost email delivery platform (now part of MessageBird). It receives email sent to configured inbound domains and relays the parsed content to a webhook endpoint. SparkPost is primarily a high-volume outbound email delivery service, and its relay webhook feature allows teams to handle reply emails and inbound contact at scale.
SparkPost Relay Webhooks is offered by MessageBird / SparkPost and is a popular choice for teams that need to process inbound email at scale. It integrates into existing workflows through routing rules, filters, and forwarding options that make it flexible for many use cases.
However, as teams grow and requirements evolve, many developers find that SparkPost Relay Webhooks introduces complexity, cost, or integration overhead that does not match what they actually need. JsonHook was designed to address these gaps by delivering every inbound email as a clean, structured JSON webhook with zero configuration required.
Pricing: 15-day free trial; paid plans start at $20/mo for 50,000 messages (outbound + inbound combined)
- Inbound-only pricing: JsonHook plans are based on inbound email volume — no outbound capacity bundled in
- Free tier: 100 emails/month at $0, no trial expiry
- No MX delegation required: Use email forwarding to route to JsonHook without changing your domain's authoritative MX records
- Automatic retries with delivery logs on all plans
- HMAC-SHA256 webhook signatures included
Limitations of SparkPost Relay Webhooks
Before committing to SparkPost Relay Webhooks for your inbound email pipeline, it is important to understand where it falls short. Development teams frequently encounter the following pain points:
- Outbound-oriented pricing: SparkPost's pricing is designed for high-volume outbound sending — using it primarily for inbound relaying means paying for capacity you do not use
- Requires domain MX record delegation: SparkPost's relay webhook requires that your domain's MX records point to SparkPost's infrastructure, creating tight platform dependency
- No automatic retry on relay failure: If your webhook endpoint is unavailable, SparkPost does not retry the relay
- Platform acquisition uncertainty: SparkPost has changed ownership multiple times (acquired by MessageBird); pricing and roadmap stability is a concern for long-term integrations
- No free tier after trial: The 15-day trial has no permanent free option for low-volume or development use
These limitations become particularly painful at scale or when building applications that require low-latency, reliable delivery of email data as structured JSON. JsonHook solves each of these issues out of the box.
Switch from SparkPost Relay Webhooks to JsonHook
Free tier: 100 emails/month. Migrate in minutes.
Get Free API KeySparkPost Relay Webhooks vs JsonHook
The following table provides a direct, feature-by-feature comparison between SparkPost Relay Webhooks and JsonHook. Both tools handle inbound email processing, but they differ significantly in approach, pricing, and developer experience.
| Feature | SparkPost Relay Webhooks | JsonHook |
|---|---|---|
| Structured JSON output | ✓ JSON payload | ✓ JSON payload |
| HMAC-SHA256 signatures | Basic signing available | ✓ Always enabled |
| Automatic retries | ✗ No retry | ✓ With backoff |
| Free tier | Trial only (15 days) | 100 emails/mo free forever |
| Inbound-only pricing | Bundled with outbound | Inbound-only plans |
| MX record flexibility | SparkPost MX required | Works with forwarding too |
| Pricing (5K emails/mo) | $20/mo (50K bundle) | $12/mo |
| Attachment handling | ✓ Included | ✓ Included |
| Platform stability | Multiple ownership changes | Independent service |
| Delivery logs | Via SparkPost API | Dedicated delivery log |
JsonHook is purpose-built for developers who want inbound email delivered as a JSON webhook endpoint call — nothing more, nothing less. There is no dashboard complexity to navigate for basic delivery, no per-message parsing fees, and no lock-in to a specific email provider SDK.
How to Migrate from SparkPost Relay Webhooks to JsonHook
Migrating from SparkPost Relay Webhooks to JsonHook is straightforward. Most teams complete the switch in under 30 minutes. Follow the steps below to move your inbound email pipeline without downtime:
- Create a JsonHook account and set up inbound addresses for each domain or recipient address you currently handle via SparkPost relay
- Configure email forwarding at your domain level to route to JsonHook addresses, avoiding the need to change MX records if you want a phased migration
- Update your webhook handler to read JsonHook's JSON payload format instead of SparkPost's relay webhook format
- Verify successful delivery in JsonHook logs, then remove the SparkPost relay webhook configuration and revert MX records if needed
Because JsonHook delivers a consistent JSON payload for every inbound email — including parsed headers, text body, HTML body, and attachment metadata — you typically need fewer lines of application code after the migration than before.
Pricing Comparison
SparkPost Relay Webhooks pricing: 15-day free trial; paid plans start at $20/mo for 50,000 messages (outbound + inbound combined). Costs can escalate quickly as email volume grows, and many plans gate key features like webhook retries or attachment handling behind higher tiers.
JsonHook offers transparent, volume-based pricing with a generous free tier that is suitable for side projects, staging environments, and low-volume production use:
| Plan | Price | Emails / Month | Features |
|---|---|---|---|
| Free | $0 | 100 | All core features, 1 address, HMAC signatures |
| Starter | $12/mo | 5,000 | 5 addresses, retries, attachment parsing |
| Pro | $39/mo | 50,000 | Unlimited addresses, priority delivery, logs |
Compared to SparkPost Relay Webhooks, JsonHook's Starter plan ($12/mo) covers the majority of small-to-medium use cases at a fraction of the cost, with no per-email parsing fees and no credit card required for the free tier.