Create a key to copy examples filled with your team.
Unique args
Pass tracking fields that come back on delivery webhooks.
Set unique_args on POST /sends. The composer writes them as X-Capsule-Unique-Args. Kumo strips that header before the message leaves. The keys are flattened onto each delivery webhook and also appear as a unique_args object.
Limits
- At most 32 keys.
- Key at most 64 bytes.
- Value at most 256 bytes.
- Scalars only. Objects and arrays are dropped.
X-Capsule-Unique-Args.json
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{
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"campaign_id": "cmp_123",
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"category": "transactional",
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"account": "team_1",
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"site": "docs"
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}
Other headers PostShiba reads
SMTP and HTTP inject can set the same data without the REST field. PostShiba also reads these, then strips them.
| Header | Description |
|---|---|
X-Capsule-Unique-Args |
JSON object. Wins on a colliding key. |
X-SMTPAPI |
JSON object. PostShiba reads unique_args inside it. |
X-Tenant-Id |
Sets tenant_id in unique args. The webhook still uses the PostShiba tenant slug. |
X-Category |
Sets category. |
X-Campaign-Id |
Sets campaign_id. |
Reserved webhook keys
Flattened keys fill blank event fields. These names stay PostShiba's. A colliding unique arg still appears inside unique_args.
eventemailtimestampsg_event_idsg_message_idsmtp-idtenant_id
event.json
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{
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"event": "delivered",
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"email": "you@example.com",
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"campaign_id": "cmp_123",
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"category": "transactional",
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"account": "team_1",
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"site": "docs",
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"unique_args": {
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"campaign_id": "cmp_123",
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"category": "transactional",
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"account": "team_1",
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"site": "docs"
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}
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}