How do I install the Install skill?

Run npx skillmds@latest add lettr-com/install in your terminal (requires Node.js), paste this page's agent-chat prompt into Claude, Cursor, or any MCP-connected agent, or download the SKILL.md file and copy it into your agent's skills directory.

Is Install safe to use?

This skill has not completed SkillMD's automated safety review yet. SkillMD never runs a skill's scripts for you; review the SKILL.md before installing.

Which AI agents work with Install?

This skill is tagged as working with Claude Code, Claude.ai, OpenAI Codex. SKILL.md is an open format, so most agents that read a skills directory can load it too.

Is Install free to use?

Yes. Installing skills from SkillMD is free, and the skill stays under its author's original license.

Who published Install?

lettr-com (@lettr-com) published this skill. Their other Agent Skills are listed on their SkillMD profile.

Install by lettr-com — Agent Skill

Name: Install
Author: lettr-com

File contents

Install Lettr

Get Lettr into the user's project: add the dependency, configure the key, make sure there's a verified domain to send from, and leave them with a working first send call.

1. Detect the stack

Use ../_shared/detect-stack.md to resolve <lang>. If nothing matches, follow its fallback (raw HTTP or SMTP relay) — there's no SDK to install in that case.

2. Install the SDK

Read ../_generated/sdk/<lang>/installation.md and follow it exactly — install command, client construction, where the key goes. It's generated from the official SDK docs, so the package name and API surface are current; don't install from memory.

For Laravel, prefer the package's own init command if the reference shows one (it writes config + env in one step).

3. Configure the API key

Ask the user for LETTR_API_KEY if it isn't already in the environment or .env. Keys start with lttr_. Put it in .env (never hardcoded), and confirm .env is gitignored.

Validate it: GET /auth/check returns the team ID on success. On 401, the key is wrong or revoked — have the user recreate it at app.lettr.com/settings/api-keys.

4. Make sure there's a verified sending domain

Sending from an unverified domain returns 400 with error_code: unconfigured_domain, and this is the single most common first-send failure. Check GET /domains. If the user's intended from domain isn't verified:

Create it (POST /domains with domain). The response carries the DNS records to add (CNAME / DKIM / return-path).
Hand those records to the user to apply at their DNS provider — this skill does not touch their registrar.
When they confirm, run POST /domains/{domain}/verify and re-check.

5. Offer a test send

Ask whether to send a real test (it sends an actual email and uses quota). If yes, send a minimal email with a verified from to an address the user controls, and confirm the response includes a request_id. For composing anything beyond a hello-world, hand off to the sending skill.

6. Report what changed

Summarize: dependency added, files edited, env vars expected, domain status, and where the first real send call should go.

Replacing an existing email provider

No per-provider migration playbook ships here. Run this install alongside the old code, then read the existing send calls and rewrite them using the sending skill + the generated SDK reference. Remove the old dependency last, after a successful send.

---name: installdescription: Use when adding Lettr to a project for the first time. Detects the stack, installs the right SDK or framework integration, configures LETTR_API_KEY, verifies a sending domain, and optionally runs a test send.---# Install LettrGet Lettr into the user's project: add the dependency, configure the key, make sure there's a verified domain to send from, and leave them with a working first send call.## 1. Detect the stackUse [`../_shared/detect-stack.md`](../_shared/detect-stack.md) to resolve `<lang>`. If nothing matches, follow its fallback (raw HTTP or SMTP relay) — there's no SDK to install in that case.## 2. Install the SDKRead [`../_generated/sdk/<lang>/installation.md`](../_generated/sdk) and follow it exactly — install command, client construction, where the key goes. It's generated from the official SDK docs, so the package name and API surface are current; don't install from memory.For Laravel, prefer the package's own init command if the reference shows one (it writes config + env in one step).## 3. Configure the API keyAsk the user for `LETTR_API_KEY` if it isn't already in the environment or `.env`. Keys start with `lttr_`. Put it in `.env` (never hardcoded), and confirm `.env` is gitignored.Validate it: `GET /auth/check` returns the team ID on success. On `401`, the key is wrong or revoked — have the user recreate it at [app.lettr.com/settings/api-keys](https://app.lettr.com/settings/api-keys).## 4. Make sure there's a verified sending domainSending from an unverified domain returns **`400`** with `error_code: unconfigured_domain`, and this is the single most common first-send failure. Check `GET /domains`. If the user's intended `from` domain isn't verified:1. Create it (`POST /domains` with `domain`). The response carries the DNS records to add (CNAME / DKIM / return-path).2. Hand those records to the user to apply at their DNS provider — this skill does not touch their registrar.3. When they confirm, run `POST /domains/{domain}/verify` and re-check.## 5. Offer a test sendAsk whether to send a real test (it sends an actual email and uses quota). If yes, send a minimal email with a verified `from` to an address the user controls, and confirm the response includes a `request_id`. For composing anything beyond a hello-world, hand off to the `sending` skill.## 6. Report what changedSummarize: dependency added, files edited, env vars expected, domain status, and where the first real send call should go.## Replacing an existing email providerNo per-provider migration playbook ships here. Run this install alongside the old code, then read the existing send calls and rewrite them using the `sending` skill + the generated SDK reference. Remove the old dependency last, after a successful send.

Frequently asked questions

Install