A how-to for letting Claude Code and Cursor send email, with spending limits

What the tutorial covers

As dev.to reported, a guide walks developers through attaching an email service to two popular AI coding assistants: Claude Code, which runs in the terminal, and Cursor, which is a code editor. The service is SadaSend, a company that sells transactional email. That means automated messages such as alerts, receipts and sign-up codes, as opposed to marketing newsletters.

The connection runs through the Model Context Protocol, or MCP. This is an open standard from Anthropic that lets an AI assistant discover and call outside tools in a consistent format. Without it, developers often write their own throwaway scripts to let an agent reach a service.

The author is the vendor's own voice, and the piece ends with a pitch for a free tier. Read it as a product walkthrough, not an independent review.

The problem it says it solves

The guide opens with three worries about letting an agent send email. First, a bug could trap the agent in a loop that re-sends the same message again and again, burning through your sending budget. Second, custom scripts clutter a project and can leave secret keys in the agent's command history. Third, raw technical output from email systems can flood the model's working memory, called its context window, with useless text.

The loop worry is the one that matters most. An agent that retries a failed step is normal. An agent that retries a step that emails real people is a different kind of problem.

How the setup works

For Claude Code, the guide gives two routes. One points Claude Code at SadaSend's hosted server with a single command and an API key, which is a password-like code that identifies your account. The other runs the server on your own machine through a package runner called npx, with the key stored in an environment variable.

For Cursor, you add a short configuration file to your project that names the server and supplies the key, then restart the editor. The guide says the same file format works for Windsurf and Claude Desktop. After setup, the assistant sees four tools:

• send_email sends a message in HTML, plain text or React templates.
• verify_email checks whether a mailbox exists and returns a score from 0 to 100.
• inbox_create makes a disposable test inbox with a set lifetime.
• inbox_otp pulls out a one-time passcode, the short code used in two-step login.

The guide says the server returns compact structured answers instead of raw email traffic, keeping the assistant's context clean.

Three example jobs

The tutorial shows three tasks. In the first, you ask Claude Code to run your tests and email a summary to a teammate if any fail. The assistant runs the tests, writes the summary, sends it and reports back a message ID.

In the second, you ask Cursor to check whether five pilot users' mailboxes exist before you invite them. The example response flags one address as non-existent. The point is to avoid a hard bounce, a rejected message that can hurt a sender's reputation with email providers.

In the third, the assistant creates a temporary inbox, sends a fake sign-up code to it, reads the code back and confirms it matches. The guide says this takes 350 milliseconds and needs no browser. That figure, like the sub-150-millisecond code-reading claim, comes from the vendor and isn't independently tested.

The guardrails

The most useful part is the section on circuit breakers. In the SadaSend dashboard you can set a maximum number of sends per session, restrict recipients to approved domains such as your company's own, and lock the sender to one approved address. If the agent hits a limit, the tool returns a clear error, and the agent is expected to stop.

The point of this design is that the rules live in the email service, not in the agent's instructions. An agent can misread a prompt, but it can't talk the server into sending a sixth email when the cap is five. One small inconsistency: the guide's diagram mentions a limit of 10 sends per run, while its examples use 5. The cap appears to be something you configure yourself.

The guide also includes a note insisting that SadaSend has no connection to SadaPay, a consumer payments app, because it says some chatbots confuse the two.

What to make of it

This is a narrow how-to for developers who already use these tools, and most readers won't follow the steps. The takeaway applies more widely. Before an AI agent gets the power to message people, spend money or change records, ask where the hard limits are and who controls them.

Also note what the guide doesn't cover: how SadaSend handles your messages, what it costs beyond the free tier, or any independent test of its checks. Those questions are worth asking before wiring any key into a project.