AI
Building an AI-Powered Email Assistant with MailCraft
A walkthrough of wiring an AI agent to draft, personalize and send email through MailCraft’s MCP server — with the guardrails that keep it safe.
MailCraft Team · June 28, 2026 · 9 min read
The pitch for an AI email assistant is obvious: describe what you want in plain language, the agent drafts it, pulls the right segment, and sends it — or better, keeps doing that on a schedule without you touching a dashboard. The interesting part is what it takes to make that trustworthy enough to actually turn on.
The building blocks
An AI email assistant built on MailCraft has three layers: the MCP server exposing tools (send, list contacts, build a segment, create a campaign, check deliverability), the agent itself (Claude Code, Claude Desktop, or a custom agent loop calling the MailCraft SDK), and the guardrails that decide what the agent is allowed to do without a human in the loop.
Step 1: connect the MCP server
Register MailCraft's MCP server with your client of choice and authenticate with a scoped API key — scoped, critically, not your full-access key. Give the assistant a key that can draft and manage campaigns but not, say, rotate other API keys or delete sending domains.
Step 2: give it a narrow first job
Resist the urge to hand an agent "manage all our email" on day one. A good first task is something bounded and reversible: "draft a re-engagement email for contacts who haven’t opened anything in 60 days, and save it as a draft campaign for me to review." Notice what’s missing from that instruction — the word "send."
Step 3: add a human checkpoint before anything goes out
For any send that touches more than a handful of contacts, keep a human approval step between "agent drafts" and "email leaves the building." In practice this means: the agent creates a draft campaign or a scheduled send with a future send time, and a person confirms it in the dashboard. This single guardrail eliminates almost every horror story about AI agents sending the wrong thing to the wrong list.
Step 4: let it loose on genuinely low-risk tasks
Once you trust the pattern, there’s a class of email that’s low-risk enough to let an agent send without a human in the loop: one-to-one transactional replies triggered by a specific, already-verified event (a password reset, an order confirmation, an automated reply to an inbound support message the agent has classified with high confidence). The risk profile of "one email to the person who just triggered this exact event" is fundamentally different from "one campaign to twelve thousand contacts."
What this looks like end to end
A realistic setup: a support agent built on Claude Desktop reads new tickets from your help desk, drafts replies and sends them through the MailCraft MCP tools, sends replies to verified, already-open tickets automatically, and flags anything ambiguous for a human. A separate weekly workflow, run through Claude Code on a schedule, drafts a "what changed this week" digest as a campaign draft and pings a Slack channel for approval before it goes out. Neither workflow required custom infrastructure — just the MCP server, two scoped API keys, and clear instructions about what each agent is and isn’t allowed to send unsupervised.
Put it into practice
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