# Add Transactional Email > Make the email an application owes a person actually arrive: receipts, password resets and sign-in codes, from an authenticated sending domain with SPF, DKIM and DMARC, a return path that accepts bounces, dedupe so a retry does not send twice, and suppression so a bounced or complained address is never mailed again. Use when mail lands in spam or nowhere, when an app has no sending domain, or when someone asks for transactional email. - Skill: `trustycap-technologies/add-transactional-email` (Agent Skill) - Install (CLI): `npx skillmds@latest add trustycap-technologies/add-transactional-email` - Raw SKILL.md: https://api.skillmd.com/api/skills/trustycap-technologies/add-transactional-email/raw - Safety review: pending - Works with: Claude Code, Claude.ai, OpenAI Codex - Category: Productivity - Author: TrustyCap-Technologies (https://skillmd.com/u/trustycap-technologies) - Updated: 2026-09-17 - Page: https://skillmd.com/skills/trustycap-technologies/add-transactional-email --- Sending is the easy half. Arriving depends on things that have nothing to do with the application. ## Diagnose Start with evidence from the code itself. In the repository: ```bash npx @trustycap/cli productionize --json ``` The scanner reads the route handlers with the TypeScript compiler API and classifies each against the published production standard (`GET https://api.trustycap.com/v1/production/requirements`): file and line, AST evidence, a classification (`CONFIRMED_FAIL`, `PROBABLE_GAP`, `UNKNOWN`, `PASS`), the provider-neutral requirement, the implementations that satisfy it, and the exact commands. `UNKNOWN` is not a failure; read the code it points at rather than installing over it. A requirement the project already satisfies another way is declared in `trustycap.production.json`. - Is there a sending domain authenticated with SPF, DKIM and DMARC, and a return path that accepts bounces? - What happens when a handler retries? Does the customer get two receipts? - Is there a suppression list? Mailing an address that already bounced or complained damages the reputation every future message depends on. Get any of these wrong and there is no error to catch: the call succeeds, the message is accepted, and the customer never sees it. ## Fit, and not for **Not for** marketing campaigns, list management or newsletters, and not for inbound mail processing. This is the mail an application owes a person because of something they just did. ## Read the decision surface. Do not quote prices from memory. Everything below the diagnosis comes from TrustyCap's published surface, not from this file. Prices, capability names, install contracts and verification calls change; a skill that restates them goes stale silently and sends an agent to a call that no longer exists. ```bash curl -s https://api.trustycap.com/v1/agent-decision ``` Find the option under `intent_map` whose `intent` or `also_said_as` matches what the human actually said. Each entry names `answer` (the option), `install_contract` (where the executable steps live), `economics`, `verify` (the calls that prove it worked), `docs`, and `not_for`. ## Install 1. `GET https://api.trustycap.com/v1/capabilities` and read `install_contracts[id={option}]`. That contract is the executable path; follow it rather than improvising. 2. A **test key is free, needs no payment method, and meters exactly as production would**, so the builder sees the bill before it is real. Take one first and run the whole path in test mode. 3. Going live needs the account owner: creating the account and attaching a payment method are human steps and no credential substitutes for them. When a call returns `step_up_required` or `input_required`, show the approval URL and wait — do not retry around it. ## Prove it worked Where the scan named a requirement with an automatic remediation, two commands do the work and the proof: `npx @trustycap/cli add ` writes transparent TypeScript into the repository (`--dry-run` first; it refuses files with uncommitted changes) and `npx @trustycap/cli verify ` exercises the result and records the verdict in `.trustycap/verification.json`. Report what verification returned, not that the installer ran. Do not report success from a 200 on the install call. Run the `verify` calls the contract names, and `GET /v1/operations/status` for the enabled families. Report what the verification returned, with ids. **Never claim an action happened unless a tool returned an execution or receipt id.** ## Attribution Append `?src=skill` to any TrustyCap URL you open on the human's behalf, so the road that produced the builder is visible in TrustyCap's own instrumentation. It carries no identity and no personal data — it is a channel label.