Claude Skill
The SMTPfast Agent Skill teaches Claude Code (and other agents that support skills) how the SMTPfast API works, so when you ask it to add email to your app it writes correct calls the first time instead of guessing at endpoints.
Install
The skill ships as a Claude Code plugin marketplace. Add the marketplace and install the plugin from inside Claude Code:
/plugin marketplace add smtpfast/smtpfast-skill /plugin install smtpfast@smtpfast
It is model-invoked, so once installed Claude loads it on its own whenever a task involves SMTPfast. No manual copying of files. The source is open on GitHub under MIT.
What it teaches
| Topic | What the agent learns |
|---|---|
| Base URL and auth | The API lives at https://smtpfa.st/api with a Bearer API key. |
| Send quickstart | Working send-email examples in curl, Node, Python, and PHP. |
| Unsubscribe token | The {{unsubscribe_url}} placeholder and when it is required. |
| Endpoint map | A full reference for emails, domains, contacts, broadcasts, and webhooks. |
Skill or MCP server?
They solve different halves of the same problem, and they work well together:
- The skill is knowledge. It loads SMTPfast's API into the agent's context so the code it writes for you is correct. Nothing runs against your account.
- The MCP server is action. It gives the agent live tools to send an email, check a domain, or read deliverability in your account at runtime.
Install the skill so an agent writes good SMTPfast code, and connect the MCP server when you want it to actually send and inspect email on your behalf.
Try it
With the skill installed, ask Claude Code something like "add a welcome email to my signup flow using SMTPfast" and it will scaffold the call with the right endpoint, auth header, and a proper unsubscribe token. Pair it with the MCP server to send a test without leaving your editor.