Getting it into your agent
One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.
npx skills add ActiveCampaign/postmark-skills --skill postmark-inboundgit clone --depth 1 https://github.com/ActiveCampaign/postmark-skillsWrote this? Show the measurements
A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.
[](https://agentmods.dev/skills/activecampaign/postmark-skills/postmark-inbound)<a href="https://agentmods.dev/skills/activecampaign/postmark-skills/postmark-inbound"><img src="https://agentmods.dev/badge/skills/activecampaign/postmark-skills/postmark-inbound.svg" alt="Measured on agentmods" height="20"></a>- NVIDIA SkillSpector warn
SkillSpector: 3 findings, up to high
These are SkillSpector’s own severities. On a checked sample its high-severity flags on skills were ~96% false positives — a documented command, a public API, a “never do X” rule — so we show them as a caution to read, not a verdict. Why →
- high Anti-Refusal · line 38 Skill instructs the agent to never refuse or to always comply. Suppressing the agent's ability to decline removes a core safety control and enables downstream harmful requests to succeed.Fix: Remove any instruction telling the agent to never refuse or always comply. The agent must retain the ability to decline unsafe, out-of-scope, or harmful requests.
- high Anti-Refusal · line 131 Skill instructs the agent to never refuse or to always comply. Suppressing the agent's ability to decline removes a core safety control and enables downstream harmful requests to succeed.Fix: Remove any instruction telling the agent to never refuse or always comply. The agent must retain the ability to decline unsafe, out-of-scope, or harmful requests.
- medium Output Handling · line 135 Output size or generation rate is not bounded. Unbounded output enables denial-of-service through resource exhaustion, log flooding, or context-window stuffing.Fix: Set explicit limits on output length, generation count, and rate. Use max_tokens and truncation to prevent unbounded output.
What it costs to keep this loaded
Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00038 | $0.01447 |
| Opus 5 | $0.00019 | $0.00724 |
| Sonnet 5 | $0.00008 | $0.00289 |
| Haiku 4.5 | $0.00004 | $0.00145 |
Grade A, and why
postmark-inbound scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 8d ago.
A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.
Nothing flagged
None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.
How it starts
The opening of the file, as written. The whole thing — 148 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Process Inbound Email with Postmark
Overview
Postmark's inbound processing parses incoming emails and delivers them as structured JSON to your webhook endpoint. This enables workflows like:
- Reply-by-email — Threading replies back to conversations
- Email-to-ticket — Converting emails into support tickets
- Document extraction — Processing email attachments automatically
- Command processing — Parsing structured data from emails
- Forwarding/routing — Routing emails to different services based on content
How It Works
- Configure an inbound address or domain in your Postmark server
- Set webhook URL where Postmark will POST parsed email data
- Receive JSON — Postmark processes the raw email and delivers structured data
- Respond with 200 — Your endpoint must return HTTP 200 to acknowledge receipt
Sender → Email → Postmark → Parses email → POST JSON → Your webhook endpoint
Quick Start
- Set up inbound domain — Configure MX records or email forwarding for your domain
- Set webhook URL — In your Postmark server settings, set the Inbound webhook URL
- Build your endpoint — Create an HTTP POST handler that accepts the inbound JSON payload
- Return 200 — Always respond with HTTP 200 to confirm receipt
Error Handling and Retries
If your endpoint returns a non-200 status code, Postmark will automatically retry delivery up to 10 times over approximately 10.5 hours with escalating intervals:
| Retry | Interval After Previous Attempt |
|---|---|
| 1 | 1 minute |
| 2 | 5 minutes |
| 3 | 10 minutes |
| 4 | 10 minutes |
| 5 | 10 minutes |
| 6 | 15 minutes |
| 7 | 30 minutes |
| 8 | 1 hour |
| 9 | 2 hours |
| 10 | 6 hours |
Important: A 403 response immediately stops all retries — Postmark interprets this as intentional rejection. After all retries are exhausted, the message is marked as "Failed" and appears as an "Inbound Error" in your activity page. You can manually retry failed messages via the API (PUT /messages/inbound/{messageid}/retry).
What ships with it
4 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.
What this file has done since we first saw it
Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.
- 8d ago First seen · 148 lines · 38 tokens per session scan A af403b26cb45
postmark-inbound is a skill published in the GitHub repository ActiveCampaign/postmark-skills (45 stars, last pushed 20d ago), licensed MIT. It adds 38 tokens to every session and 1,447 once invoked, about $0.0002 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.
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