feat: add smtp adapter (#279)

lib/notification/adapter/smtp.js

@@ -0,0 +1,112 @@
+/*
+ * Copyright (c) 2026 by Christian Kellner.
+ * Licensed under Apache-2.0 with Commons Clause and Attribution/Naming Clause
+ */
+
+import nodemailer from 'nodemailer';
+import path from 'path';
+import fs from 'fs';
+import Handlebars from 'handlebars';
+import { markdown2Html } from '../../services/markdown.js';
+import { getDirName, normalizeImageUrl } from '../../utils.js';
+
+const __dirname = getDirName();
+const template = fs.readFileSync(path.resolve(__dirname + '/notification/emailTemplate/template.hbs'), 'utf8');
+const emailTemplate = Handlebars.compile(template);
+
+const mapListings = (serviceName, jobKey, listings) =>
+  listings.map((l) => {
+    const image = normalizeImageUrl(l.image);
+    return {
+      title: l.title || '',
+      link: l.link || '',
+      address: l.address || '',
+      size: l.size || '',
+      price: l.price || '',
+      image,
+      hasImage: Boolean(image),
+      serviceName,
+      jobKey,
+    };
+  });
+
+export const send = async ({ serviceName, newListings, notificationConfig, jobKey }) => {
+  const { host, port, secure, username, password, receiver, from } = notificationConfig.find(
+    (adapter) => adapter.id === config.id,
+  ).fields;
+
+  const to = receiver
+    .trim()
+    .split(',')
+    .map((r) => r.trim())
+    .filter(Boolean);
+
+  const transporter = nodemailer.createTransport({
+    host,
+    port: Number(port),
+    secure: secure === 'true',
+    auth: {
+      user: username,
+      pass: password,
+    },
+  });
+
+  const listings = mapListings(serviceName, jobKey, newListings);
+
+  const html = emailTemplate({
+    serviceName: `Job: (${jobKey}) | Service: ${serviceName}`,
+    numberOfListings: listings.length,
+    listings,
+  });
+
+  return transporter.sendMail({
+    from,
+    to: to.join(','),
+    subject: `Fredy found ${listings.length} new listing(s) for ${serviceName}`,
+    html,
+  });
+};
+
+export const config = {
+  id: 'smtp',
+  name: 'SMTP',
+  description: 'Send notifications via any SMTP server using Nodemailer.',
+  readme: markdown2Html('lib/notification/adapter/smtp.md'),
+  fields: {
+    host: {
+      type: 'text',
+      label: 'SMTP Host',
+      description: 'The hostname of the SMTP server (e.g., smtp.gmail.com).',
+    },
+    port: {
+      type: 'text',
+      label: 'SMTP Port',
+      description: 'The port of the SMTP server (e.g., 587 for STARTTLS, 465 for SSL).',
+    },
+    secure: {
+      type: 'text',
+      label: 'Secure (SSL/TLS)',
+      description: 'Set to "true" for port 465 (SSL). Leave empty or "false" for STARTTLS on port 587.',
+    },
+    username: {
+      type: 'text',
+      label: 'Username',
+      description: 'The username for SMTP authentication.',
+    },
+    password: {
+      type: 'text',
+      label: 'Password',
+      description: 'The password (or app password) for SMTP authentication.',
+    },
+    receiver: {
+      type: 'text',
+      label: 'Receiver Email(s)',
+      description: 'Comma-separated email addresses Fredy will send notifications to.',
+    },
+    from: {
+      type: 'email',
+      label: 'Sender Email',
+      description: 'The email address Fredy sends from.',
+    },
+  },
+};

lib/notification/adapter/smtp.md

@@ -0,0 +1,22 @@
+### SMTP Adapter
+
+Send notifications through any SMTP server using [Nodemailer](https://nodemailer.com/).
+This works with Gmail, Outlook, self-hosted mail servers, or any provider that supports SMTP.
+
+Setup:
+
+- Provide the SMTP host and port of your mail server.
+- For **SSL/TLS** (port 465), set Secure to `true`.
+- For **STARTTLS** (port 587), leave Secure empty or set it to `false`.
+- Enter the username and password for authentication. For Gmail, use an [App Password](https://support.google.com/accounts/answer/185833).
+- Set the sender email address (must be allowed by your SMTP server).
+
+Multiple recipients:
+
+- Separate email addresses with commas (e.g., `some@email.com`, `someOther@email.com`).
+
+Common SMTP settings:
+
+- **Gmail** — `smtp.gmail.com`, port 587, secure: false
+- **Outlook** — `smtp.office365.com`, port 587, secure: false
+- **Yahoo** — `smtp.mail.yahoo.com`, port 465, secure: true