Send email using MailChannels Email API

**Judgement:** A solid, focused skill for teams already using or choosing MailChannels, offering both sending and delivery-event ingestion with good attention to verification and correlation, but requiring careful setup. **Strengths & Risks** - **Strengths:** - Covers both `/send` and `/send-async` plus webhook endpoints, so you get full lifecycle visibility. - Encourages best practices: DNS domain-lock TXT records, correlation ID persistence, and ed25519 signature verification using MailChannels’ public keys. - Integrates with Moltbot hooks, enabling downstream automation on delivery/bounce events. - **Risks / Limitations:** - Operational complexity: you must correctly configure environment variables, DNS TXT records, webhook endpoints, and signature verification; mistakes can lead to delivery failures or untrusted events. - Security risk if `MAILCHANNELS_API_KEY` is mishandled or if webhook verification is implemented incorrectly (e.g., skipping or partially validating signatures). - Depends entirely on MailChannels availability and your webhook endpoint robustness (retry handling, deduplication, storage). **Recommended Scenarios** - Good fit for: teams committed to MailChannels needing reliable, event-driven email delivery tracking inside OpenClaw/Clawdbot, and who are comfortable managing DNS, webhooks, and cryptographic verification. - Less ideal for: simple or low-volume use cases where plain SMTP or a simpler provider integration is sufficient, or teams without the capacity to correctly implement and monitor webhook verification and DNS/domain-lock configuration.