Astro Endpoint for sending emails via Gmail SMTP username + app password, via nodemailer (NodeJS)

email.ts

import type { APIRoute } from "astro";
import type SMTPTransport from "nodemailer/lib/smtp-transport";
import nodemailer from "nodemailer";

/****
envs:
GMAIL_APP_PW=
GMAIL_ACCOUNT=
GMAIL_TO=
*/

/****
Re: GMail SMTP, see: 
- https://community.cloudflare.com/t/solved-how-to-use-gmail-smtp-to-send-from-an-email-address-which-uses-cloudflare-email-routing/382769
- https://myaccount.google.com/apppasswords
*/

interface PostBody {
  from: string;
  name: string;
  text: string;
  answer?: string;
}

function makeResponse200(message?: string) {
  if (message) {
    return new Response(JSON.stringify({ message }), { status: 200 });
  }
  return new Response(JSON.stringify({ ok: true }), { status: 200 });
}

const makeMessage = (
  from: string,
  name: string,
  text: string,
  to = import.meta.env.GMAIL_TO
) => ({
  from: `"${from}" <${import.meta.env.GMAIL_ACCOUNT}>`,
  to,
  subject: `Website Email from: ${name}`,
  text,
  html: `<p>${text.replaceAll(/\r?\n/g, "<br>")}</p>`,
});

const smtpConfig = "smtps://" + import.meta.env.GMAIL_ACCOUNT + ":" + import.meta.env.GMAIL_APP_PW + "@smtp.gmail.com/`;

const _post = async ({ from, name, text }: PostBody): Promise<SMTPTransport.SentMessageInfo> => {
  const transporter = nodemailer.createTransport(smtpConfig);
  return transporter.sendMail(makeMessage(from, name, text));
};

export const post: APIRoute = async function post({ request }) {
  let doSend = request.headers.get("Content-Type") === "application/json";
  if (!doSend) {
    return makeResponse200("json");
  }

  const body = (await request.json()) as PostBody;

  // validate honeypot
  // Challenge question: "Today's Day of Month Is..."
  const { answer } = body;
  // Note: buffer by +/-1 day to handle diff time zones
  doSend = Math.abs(new Date().getDate() - Number(answer)) <= 1;
  if (!doSend) {
    return makeResponse200(answer);
  }

  let { from, name, text } = body;
  doSend = Boolean(from && name && text);
  if (!doSend) {
    return makeResponse200("body");
  }

  [from, name, text] = [from, name, text].map(
    (t, i) => t.slice(0, 50 + 200 * i) // do some VERY basic input sanitization
  );

  await _post({ from, name, text }).catch((err) => {
    // TODO: needs better error handling!
    console.error({ smtpConfig, err: err.message });
  });

  return makeResponse200(`${from} : ${name}`);
};