Switch in an afternoon. Keep the code you have.

import { Waymail } from "waymail";

const waymail = new Waymail(process.env.WAYMAIL_API_KEY);

const { id } = await waymail.emails.send({
  from: "Acme <hello@acme.com>",
  to: "user@example.com",
  subject: "Verify your account",
  html: "<p>Thanks for signing up.</p>",
});
// → { id: "em_eu_01K4…", status: "queued" }

# keep using the resend package — two variables, no code change
RESEND_API_KEY=re_…
RESEND_API_KEY=wm_eu_live_…
RESEND_BASE_URL=https://eu.api.waymail.app

curl https://eu.api.waymail.app/emails \
  -H "Authorization: Bearer $WAYMAIL_API_KEY" \
  -H "Idempotency-Key: welcome:u_8813" \
  -H "Content-Type: application/json" \
  -d '{ "from": "Acme <hello@acme.com>", "to": "user@example.com",
        "subject": "Verify your account", "html": "<p>Thanks for signing up.</p>" }'
# → 202 { "id": "em_eu_01K4…", "status": "queued" }

# Claude Code, Cursor and your own agents: an API key
claude mcp add --transport http waymail https://eu.mcp.waymail.app/mcp \
  --header "Authorization: Bearer $WAYMAIL_API_KEY"

# Claude.ai and ChatGPT: add https://eu.mcp.waymail.app/mcp as a connector and sign in