Add local sendmail fallback so mailer works internally without external services

src/lib/services/email.ts

@@ -1,3 +1,4 @@
+import { exec } from "child_process";
 import nodemailer, { type Transporter } from "nodemailer";
 import { Resend } from "resend";
 import { env } from "@/env";
@@ -24,7 +25,33 @@ function getResend(): Resend | null {
   return resend;
 }
 
-/** Send an HTML email. Tries Resend first, then SMTP. Returns false if both are unconfigured. */
+function sendViaSendmail(to: string, subject: string, html: string, from: string): Promise<boolean> {
+  return new Promise((resolve) => {
+    const headers = [
+      `From: ${from}`,
+      `To: ${to}`,
+      `Subject: ${subject}`,
+      "MIME-Version: 1.0",
+      'Content-Type: text/html; charset="UTF-8"',
+    ].join("\r\n");
+
+    const child = exec("sendmail -t", (error) => {
+      if (error) {
+        console.error("[email] sendmail failed:", error.message);
+        resolve(false);
+      } else {
+        resolve(true);
+      }
+    });
+
+    if (child.stdin) {
+      child.stdin.write(`${headers}\r\n\r\n${html}`);
+      child.stdin.end();
+    }
+  });
+}
+
+/** Send an HTML email. Tries Resend → SMTP → local sendmail. Returns false if all fail. */
 export async function sendMail(to: string, subject: string, html: string): Promise<boolean> {
   const from = env.SMTP_FROM ?? `no-reply@${env.HOTEL_NAME}`;
 
@@ -48,8 +75,11 @@ export async function sendMail(to: string, subject: string, html: string): Promi
     }
   }
 
+  const ok = await sendViaSendmail(to, subject, html, from);
+  if (ok) return true;
+
   if (!r && !t) {
-    console.warn("[email] No mailer configured — set RESEND_API_KEY or SMTP_HOST");
+    console.warn("[email] No mailer configured — set RESEND_API_KEY or SMTP_HOST, or install sendmail");
   }
   return false;
 }