Feature: Rechnungsversand per E-Mail (eigener SMTP-Client, kein PHPMailer)

migrations/039_smtp_settings.sql

@@ -0,0 +1,8 @@
+ALTER TABLE company_settings
+  ADD COLUMN IF NOT EXISTS mail_smtp_host       VARCHAR(255) NOT NULL DEFAULT '' AFTER nextcloud_done,
+  ADD COLUMN IF NOT EXISTS mail_smtp_port       SMALLINT UNSIGNED NOT NULL DEFAULT 587 AFTER mail_smtp_host,
+  ADD COLUMN IF NOT EXISTS mail_smtp_encryption VARCHAR(10)  NOT NULL DEFAULT 'tls' AFTER mail_smtp_port,
+  ADD COLUMN IF NOT EXISTS mail_smtp_user       VARCHAR(255) NOT NULL DEFAULT '' AFTER mail_smtp_encryption,
+  ADD COLUMN IF NOT EXISTS mail_smtp_pass       VARCHAR(255) NOT NULL DEFAULT '' AFTER mail_smtp_user,
+  ADD COLUMN IF NOT EXISTS mail_from_name       VARCHAR(255) NOT NULL DEFAULT '' AFTER mail_smtp_pass,
+  ADD COLUMN IF NOT EXISTS mail_from_email      VARCHAR(255) NOT NULL DEFAULT '' AFTER mail_from_name;

public/index.php

@@ -103,6 +103,7 @@ $router->post('/invoices/{id}/cancel', fn($p) => (new InvoiceController())->canc
 $router->post('/invoices/{id}/delete', fn($p) => (new InvoiceController())->destroy($p));
 $router->post('/invoices/{id}/lines', fn($p) => (new InvoiceController())->addLine($p));
 $router->post('/invoices/{id}/lines/{line_id}/delete', fn($p) => (new InvoiceController())->deleteLine($p));
+$router->post('/invoices/{id}/send', fn($p) => (new InvoiceController())->send($p));
 
 // ── Anlagevermögen ───────────────────────────────────────────
 $router->get('/assets',                       fn($p) => (new AssetController())->index($p));
@@ -130,6 +131,7 @@ $router->get('/tax/euer/{year}/konto/{konto_id}', fn($p) => (new EuerController(
 // ── Einstellungen ────────────────────────────────────────────
 $router->get('/settings', fn($p) => (new SettingsController())->show($p));
 $router->post('/settings', fn($p) => (new SettingsController())->update($p));
+$router->post('/settings/mail-test', fn($p) => (new SettingsController())->mailTest($p));
 $router->post('/settings/logo', fn($p) => (new SettingsController())->uploadLogo($p));
 $router->post('/settings/logo/delete', fn($p) => (new SettingsController())->deleteLogo($p));
 

src/Controllers/InvoiceController.php

@@ -10,6 +10,7 @@ use Steuerkram\Models\Beleg;
 use Steuerkram\Models\Booking;
 use Steuerkram\Models\Account;
 use Steuerkram\Models\Setting;
+use Steuerkram\Services\EmailService;
 use Steuerkram\Services\PdfInvoiceService;
 use Steuerkram\View;
 
@@ -197,6 +198,50 @@ class InvoiceController
         }
     }
 
+    public function send(array $params): void
+    {
+        $id      = (int)$params['id'];
+        $invoice = Invoice::find($id);
+        if (!$invoice) { http_response_code(404); return; }
+
+        if ($invoice['status'] === 'Entwurf') {
+            View::redirect("/invoices/{$id}", 'Entwürfe können nicht gesendet werden.', 'error');
+            return;
+        }
+
+        // Empfänger aus POST (bis zu 3), Fallback: Kunden-E-Mail
+        $recipients = array_values(array_filter(array_map(
+            'trim',
+            array_merge(
+                [$_POST['email_to'] ?? $invoice['email'] ?? ''],
+                [$_POST['email_cc1'] ?? ''],
+                [$_POST['email_cc2'] ?? ''],
+            )
+        )));
+
+        if (empty($recipients)) {
+            View::redirect("/invoices/{$id}", 'Keine Empfänger-E-Mail-Adresse angegeben.', 'error');
+            return;
+        }
+
+        try {
+            $lines    = Invoice::lines($id);
+            $settings = Setting::get();
+            (new EmailService())->sendInvoice($invoice, $lines, $settings, $recipients);
+
+            if ($invoice['status'] === 'Finalisiert') {
+                \Steuerkram\Database::execute(
+                    "UPDATE invoices SET status='Gesendet', updated_at=NOW() WHERE id=?",
+                    [$id]
+                );
+            }
+
+            View::redirect("/invoices/{$id}", 'Rechnung erfolgreich gesendet.');
+        } catch (\RuntimeException $e) {
+            View::redirect("/invoices/{$id}", 'Fehler beim Senden: ' . $e->getMessage(), 'error');
+        }
+    }
+
     public function pdf(array $params): void
     {
         $invoice  = Invoice::find((int)$params['id']);

src/Controllers/SettingsController.php

@@ -5,6 +5,7 @@ declare(strict_types=1);
 namespace Steuerkram\Controllers;
 
 use Steuerkram\Models\Setting;
+use Steuerkram\Services\EmailService;
 use Steuerkram\View;
 
 class SettingsController
@@ -89,6 +90,25 @@ class SettingsController
         View::redirect('/settings', 'Logo hochgeladen.');
     }
 
+    public function mailTest(array $params): void
+    {
+        header('Content-Type: application/json');
+        $settings = Setting::get();
+        $to       = $settings['email'] ?? '';
+
+        if (empty($to)) {
+            echo json_encode(['error' => 'Keine Firmen-E-Mail hinterlegt (Einstellungen → Firmendaten).']);
+            return;
+        }
+
+        try {
+            (new EmailService())->sendTestMail($settings, $to);
+            echo json_encode(['ok' => true]);
+        } catch (\RuntimeException $e) {
+            echo json_encode(['error' => $e->getMessage()]);
+        }
+    }
+
     public function deleteLogo(array $params): void
     {
         Setting::deleteLogo();

src/Models/Setting.php

@@ -36,6 +36,9 @@ class Setting
                 payment_days_default=?, test_mode=?, ki_vorschlag_aktiv=?,
                 nextcloud_url=?, nextcloud_user=?, nextcloud_pass=?,
                 nextcloud_folder=?, nextcloud_done=?,
+                mail_smtp_host=?, mail_smtp_port=?, mail_smtp_encryption=?,
+                mail_smtp_user=?, mail_smtp_pass=?,
+                mail_from_name=?, mail_from_email=?,
                 logo_max_width=?, logo_max_height=?,
                 logo_position=?, logo_margin_side=?, logo_margin_top=?
              WHERE id=1',
@@ -68,6 +71,13 @@ class Setting
                 $data['nextcloud_pass'] ?: null,
                 $data['nextcloud_folder'] ?: '/Belege/Import',
                 $data['nextcloud_done'] ?: null,
+                $data['mail_smtp_host'] ?: '',
+                (int)($data['mail_smtp_port'] ?? 587),
+                in_array($data['mail_smtp_encryption'] ?? '', ['tls', 'ssl', 'none']) ? $data['mail_smtp_encryption'] : 'tls',
+                $data['mail_smtp_user'] ?: '',
+                $data['mail_smtp_pass'] ?: '',
+                $data['mail_from_name'] ?: '',
+                $data['mail_from_email'] ?: '',
                 max(50, (int)($data['logo_max_width'] ?? 600)),
                 max(20, (int)($data['logo_max_height'] ?? 100)),
                 $logoPosition,

src/Services/EmailService.php

@@ -0,0 +1,68 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Steuerkram\Services;
+
+class EmailService
+{
+    /**
+     * Sendet eine Rechnung als PDF-Anhang an alle Empfänger.
+     *
+     * @param string[] $recipients  E-Mail-Adressen (1–3)
+     * @throws \RuntimeException
+     */
+    public function sendInvoice(array $invoice, array $lines, array $settings, array $recipients): void
+    {
+        $mailer = $this->buildMailer($settings);
+
+        $pdfService = new PdfInvoiceService();
+        $pdfContent = $pdfService->renderToString($invoice, $lines, $settings);
+
+        $nr       = $invoice['rechnungs_nr'] ?? 'Entwurf';
+        $firma    = $settings['firma'] ?? '';
+        $subject  = 'Rechnung ' . $nr;
+        $filename = 'Rechnung-' . $nr . '.pdf';
+
+        $body = "Guten Tag,\n\n"
+            . "anbei erhalten Sie die Rechnung {$nr} von {$firma}.\n\n"
+            . "Bei Fragen stehen wir Ihnen gerne zur Verfügung.\n\n"
+            . "Mit freundlichen Grüßen\n"
+            . $firma;
+
+        $mailer->send($recipients, $subject, $body, $pdfContent, $filename);
+    }
+
+    /**
+     * Sendet eine Test-Mail an die angegebene Adresse.
+     *
+     * @throws \RuntimeException
+     */
+    public function sendTestMail(array $settings, string $to): void
+    {
+        $mailer = $this->buildMailer($settings);
+        $mailer->send(
+            [$to],
+            'Steuerkram – SMTP-Test',
+            "Die SMTP-Konfiguration funktioniert korrekt.\n\nDiese Mail wurde von Steuerkram gesendet."
+        );
+    }
+
+    private function buildMailer(array $settings): SmtpMailer
+    {
+        $host = $settings['mail_smtp_host'] ?? '';
+        if (empty($host)) {
+            throw new \RuntimeException('SMTP-Host ist nicht konfiguriert.');
+        }
+
+        return new SmtpMailer(
+            host:       $host,
+            port:       (int)($settings['mail_smtp_port'] ?? 587),
+            encryption: $settings['mail_smtp_encryption'] ?? 'tls',
+            user:       $settings['mail_smtp_user'] ?? '',
+            pass:       $settings['mail_smtp_pass'] ?? '',
+            fromEmail:  $settings['mail_from_email'] ?: ($settings['email'] ?? ''),
+            fromName:   $settings['mail_from_name']  ?: ($settings['firma'] ?? ''),
+        );
+    }
+}

src/Services/PdfInvoiceService.php

@@ -8,7 +8,24 @@ use Mpdf\Mpdf;
 
 class PdfInvoiceService
 {
+    public function renderToString(array $invoice, array $lines, array $settings): string
+    {
+        return $this->generate($invoice, $lines, $settings);
+    }
+
     public function render(array $invoice, array $lines, array $settings): void
+    {
+        $pdfContent = $this->generate($invoice, $lines, $settings);
+        $filename   = 'Rechnung-' . ($invoice['rechnungs_nr'] ?? 'Entwurf') . '.pdf';
+
+        header('Content-Type: application/pdf');
+        header('Content-Disposition: attachment; filename="' . $filename . '"');
+        header('Content-Length: ' . strlen($pdfContent));
+        echo $pdfContent;
+        exit;
+    }
+
+    private function generate(array $invoice, array $lines, array $settings): string
     {
         $html = $this->buildHtml($invoice, $lines, $settings);
 
@@ -40,18 +57,11 @@ class PdfInvoiceService
         $mpdf->WriteHTML($this->buildCss(), \Mpdf\HTMLParserMode::HEADER_CSS);
         $mpdf->WriteHTML($html, \Mpdf\HTMLParserMode::HTML_BODY);
 
-        $filename   = 'Rechnung-' . ($invoice['rechnungs_nr'] ?? 'Entwurf') . '.pdf';
         $pdfContent = $mpdf->Output('', 'S');
 
         // ZUGFeRD EN16931-XML einbetten (E-Rechnung)
-        $zugferd    = new ZugferdService();
+        $zugferd = new ZugferdService();
-        $pdfContent = $zugferd->attachToPdf($pdfContent, $invoice, $lines, $settings);
+        return $zugferd->attachToPdf($pdfContent, $invoice, $lines, $settings);
-
-        header('Content-Type: application/pdf');
-        header('Content-Disposition: attachment; filename="' . $filename . '"');
-        header('Content-Length: ' . strlen($pdfContent));
-        echo $pdfContent;
-        exit;
     }
 
     private function buildHtml(array $inv, array $lines, array $settings): string

src/Services/SmtpMailer.php

@@ -0,0 +1,237 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Steuerkram\Services;
+
+/**
+ * Schlanker SMTP-Client ohne externe Abhängigkeiten.
+ * Unterstützt STARTTLS (port 587), SSL/TLS (port 465) und unverschlüsselt.
+ * AUTH LOGIN und AUTH PLAIN. Bis zu n Empfänger. Einen Anhang (binary string).
+ */
+class SmtpMailer
+{
+    /** @var resource */
+    private $sock;
+
+    public function __construct(
+        private readonly string $host,
+        private readonly int    $port,
+        private readonly string $encryption, // 'tls' | 'ssl' | 'none'
+        private readonly string $user,
+        private readonly string $pass,
+        private readonly string $fromEmail,
+        private readonly string $fromName,
+    ) {}
+
+    /**
+     * @param string[]    $to        Liste von Empfänger-Adressen (max. 3)
+     * @param string      $subject
+     * @param string      $body      Plain-Text-Body
+     * @param string|null $attachContent  Binärer Inhalt des Anhangs
+     * @param string|null $attachName     Dateiname des Anhangs
+     * @throws \RuntimeException
+     */
+    public function send(
+        array   $to,
+        string  $subject,
+        string  $body,
+        ?string $attachContent = null,
+        ?string $attachName    = null,
+    ): void {
+        $this->connect();
+        $this->authenticate();
+        $this->sendMessage($to, $subject, $body, $attachContent, $attachName);
+        $this->cmd('QUIT');
+        fclose($this->sock);
+    }
+
+    // ── Verbindung ───────────────────────────────────────────────
+
+    private function connect(): void
+    {
+        $address = $this->encryption === 'ssl'
+            ? 'ssl://' . $this->host
+            : 'tcp://' . $this->host;
+
+        $ctx = stream_context_create([
+            'ssl' => [
+                'verify_peer'       => true,
+                'verify_peer_name'  => true,
+                'allow_self_signed' => false,
+            ],
+        ]);
+
+        $sock = stream_socket_client(
+            $address . ':' . $this->port,
+            $errno, $errstr, 15,
+            STREAM_CLIENT_CONNECT,
+            $ctx
+        );
+
+        if (!$sock) {
+            throw new \RuntimeException("SMTP-Verbindung fehlgeschlagen: {$errstr} ({$errno})");
+        }
+
+        $this->sock = $sock;
+        stream_set_timeout($this->sock, 15);
+
+        $this->expect(220);
+        $this->ehlo();
+
+        if ($this->encryption === 'tls') {
+            $this->cmd('STARTTLS');
+            $this->expect(220);
+            if (!stream_socket_enable_crypto($this->sock, true, STREAM_CRYPTO_METHOD_TLS_CLIENT)) {
+                throw new \RuntimeException('STARTTLS-Aushandlung fehlgeschlagen.');
+            }
+            $this->ehlo();
+        }
+    }
+
+    private function ehlo(): void
+    {
+        $this->cmd('EHLO ' . (gethostname() ?: 'localhost'));
+        $this->expectMulti(250);
+    }
+
+    // ── Authentifizierung ────────────────────────────────────────
+
+    private function authenticate(): void
+    {
+        $this->cmd('AUTH LOGIN');
+        $this->expect(334);
+        $this->cmd(base64_encode($this->user));
+        $this->expect(334);
+        $this->cmd(base64_encode($this->pass));
+        $this->expect(235);
+    }
+
+    // ── Nachricht ────────────────────────────────────────────────
+
+    private function sendMessage(
+        array   $to,
+        string  $subject,
+        string  $body,
+        ?string $attachContent,
+        ?string $attachName,
+    ): void {
+        $this->cmd('MAIL FROM:<' . $this->fromEmail . '>');
+        $this->expect(250);
+
+        foreach ($to as $addr) {
+            $this->cmd('RCPT TO:<' . $addr . '>');
+            $this->expect(250);
+        }
+
+        $this->cmd('DATA');
+        $this->expect(354);
+
+        $raw = $this->buildMessage($to, $subject, $body, $attachContent, $attachName);
+
+        // Dot-Stuffing: Zeilen, die mit '.' beginnen, bekommen einen zweiten Punkt
+        $raw = preg_replace('/^\.$/m', '..', $raw);
+
+        fwrite($this->sock, $raw . "\r\n.\r\n");
+        $this->expect(250);
+    }
+
+    private function buildMessage(
+        array   $to,
+        string  $subject,
+        string  $body,
+        ?string $attachContent,
+        ?string $attachName,
+    ): string {
+        $date     = date('r');
+        $fromHdr  = $this->encodeHeader($this->fromName) . ' <' . $this->fromEmail . '>';
+        $toHdr    = implode(', ', $to);
+        $subjHdr  = $this->encodeHeader($subject);
+        $msgId    = '<' . uniqid('sk', true) . '@' . (gethostname() ?: 'localhost') . '>';
+
+        if ($attachContent === null) {
+            return implode("\r\n", [
+                'Date: '       . $date,
+                'Message-ID: ' . $msgId,
+                'From: '       . $fromHdr,
+                'To: '         . $toHdr,
+                'Subject: '    . $subjHdr,
+                'MIME-Version: 1.0',
+                'Content-Type: text/plain; charset=UTF-8',
+                'Content-Transfer-Encoding: quoted-printable',
+                '',
+                $this->quotedPrintable($body),
+            ]);
+        }
+
+        $boundary = '----=_Part_' . bin2hex(random_bytes(8));
+        $b64      = chunk_split(base64_encode($attachContent), 76, "\r\n");
+        $safeName = $this->encodeHeader($attachName ?? 'Anhang.pdf');
+
+        return implode("\r\n", [
+            'Date: '       . $date,
+            'Message-ID: ' . $msgId,
+            'From: '       . $fromHdr,
+            'To: '         . $toHdr,
+            'Subject: '    . $subjHdr,
+            'MIME-Version: 1.0',
+            'Content-Type: multipart/mixed; boundary="' . $boundary . '"',
+            '',
+            '--' . $boundary,
+            'Content-Type: text/plain; charset=UTF-8',
+            'Content-Transfer-Encoding: quoted-printable',
+            '',
+            $this->quotedPrintable($body),
+            '',
+            '--' . $boundary,
+            'Content-Type: application/pdf; name="' . $safeName . '"',
+            'Content-Transfer-Encoding: base64',
+            'Content-Disposition: attachment; filename="' . $safeName . '"',
+            '',
+            $b64,
+            '--' . $boundary . '--',
+        ]);
+    }
+
+    // ── Hilfsmethoden ────────────────────────────────────────────
+
+    private function cmd(string $line): void
+    {
+        fwrite($this->sock, $line . "\r\n");
+    }
+
+    private function expect(int $code): string
+    {
+        $response = fgets($this->sock, 512);
+        if ($response === false) {
+            throw new \RuntimeException('SMTP: Keine Antwort vom Server.');
+        }
+        if ((int)$response !== $code) {
+            throw new \RuntimeException('SMTP: Unerwartete Antwort: ' . trim($response));
+        }
+        return $response;
+    }
+
+    /** Liest mehrzeilige SMTP-Antworten (z.B. nach EHLO) */
+    private function expectMulti(int $code): void
+    {
+        do {
+            $line = fgets($this->sock, 512);
+            if ($line === false) throw new \RuntimeException('SMTP: Verbindung unterbrochen.');
+            if ((int)$line !== $code) throw new \RuntimeException('SMTP: ' . trim($line));
+        } while ($line[3] === '-');
+    }
+
+    private function encodeHeader(string $value): string
+    {
+        if (mb_detect_encoding($value, 'ASCII', true)) {
+            return $value;
+        }
+        return '=?UTF-8?B?' . base64_encode($value) . '?=';
+    }
+
+    private function quotedPrintable(string $text): string
+    {
+        return quoted_printable_encode($text);
+    }
+}

src/Views/invoices/show.php

@@ -31,7 +31,11 @@ $badgeClass = match($invoice['status']) {
             </form>
         <?php endif; ?>
         <?php if ($invoice['status'] !== 'Entwurf'): ?>
-            <a href="/invoices/<?= $h($invoice['id']) ?>/pdf" class="btn btn-primary">PDF herunterladen</a>
+            <a href="/invoices/<?= $h($invoice['id']) ?>/pdf" class="btn btn-secondary">PDF herunterladen</a>
+        <?php endif; ?>
+        <?php if (!in_array($invoice['status'], ['Entwurf', 'Storniert'])): ?>
+            <button type="button" class="btn btn-primary"
+                    onclick="document.getElementById('send-modal').style.display='flex'">Per E-Mail senden</button>
         <?php endif; ?>
         <?php if ($invoice['status'] === 'Gesendet'): ?>
             <a href="/invoices/<?= $h($invoice['id']) ?>/book" class="btn btn-success">Zahlungseingang erfassen</a>
@@ -311,3 +315,31 @@ $badgeClass = match($invoice['status']) {
     }
 }());
 </script>
+
+<!-- E-Mail-Senden-Modal -->
+<div id="send-modal" style="display:none;position:fixed;inset:0;background:rgba(0,0,0,.45);z-index:1000;align-items:center;justify-content:center">
+    <div style="background:#fff;border-radius:8px;padding:1.5rem;width:420px;max-width:95vw;box-shadow:0 8px 32px rgba(0,0,0,.2)">
+        <h3 style="margin:0 0 1rem">Rechnung per E-Mail senden</h3>
+        <form method="post" action="/invoices/<?= $h($invoice['id']) ?>/send">
+            <div class="form-group">
+                <label>Empfänger *</label>
+                <input type="email" name="email_to" required
+                       value="<?= $h($invoice['email'] ?? '') ?>"
+                       placeholder="empfaenger@example.com">
+            </div>
+            <div class="form-group">
+                <label>CC 1 <span style="font-weight:normal;color:#888">(optional)</span></label>
+                <input type="email" name="email_cc1" placeholder="cc1@example.com">
+            </div>
+            <div class="form-group">
+                <label>CC 2 <span style="font-weight:normal;color:#888">(optional)</span></label>
+                <input type="email" name="email_cc2" placeholder="cc2@example.com">
+            </div>
+            <div style="display:flex;gap:.75rem;justify-content:flex-end;margin-top:1.25rem">
+                <button type="button" class="btn btn-secondary"
+                        onclick="document.getElementById('send-modal').style.display='none'">Abbrechen</button>
+                <button type="submit" class="btn btn-primary">Senden</button>
+            </div>
+        </form>
+    </div>
+</div>

src/Views/settings/form.php

@@ -256,11 +256,84 @@
             </div>
         </div>
 
+        <!-- E-Mail-Versand -->
+        <div class="card mb-2">
+            <div class="card-header"><div class="card-title">E-Mail-Versand (SMTP)</div></div>
+            <div class="card-body">
+                <div class="form-group">
+                    <label>SMTP-Host</label>
+                    <input type="text" name="mail_smtp_host" value="<?= $h($settings['mail_smtp_host'] ?? '') ?>" placeholder="smtp.example.com">
+                </div>
+                <div class="form-grid form-grid-2">
+                    <div class="form-group">
+                        <label>Port</label>
+                        <input type="number" name="mail_smtp_port" value="<?= $h($settings['mail_smtp_port'] ?? 587) ?>" min="1" max="65535">
+                    </div>
+                    <div class="form-group">
+                        <label>Verschlüsselung</label>
+                        <select name="mail_smtp_encryption">
+                            <option value="tls"  <?= ($settings['mail_smtp_encryption'] ?? 'tls') === 'tls'  ? 'selected' : '' ?>>STARTTLS (Port 587)</option>
+                            <option value="ssl"  <?= ($settings['mail_smtp_encryption'] ?? '')     === 'ssl'  ? 'selected' : '' ?>>SSL/TLS (Port 465)</option>
+                            <option value="none" <?= ($settings['mail_smtp_encryption'] ?? '')     === 'none' ? 'selected' : '' ?>>Keine</option>
+                        </select>
+                    </div>
+                </div>
+                <div class="form-grid form-grid-2">
+                    <div class="form-group">
+                        <label>SMTP-Benutzername</label>
+                        <input type="text" name="mail_smtp_user" value="<?= $h($settings['mail_smtp_user'] ?? '') ?>" autocomplete="off">
+                    </div>
+                    <div class="form-group">
+                        <label>SMTP-Passwort</label>
+                        <input type="password" name="mail_smtp_pass" value="<?= $h($settings['mail_smtp_pass'] ?? '') ?>" autocomplete="new-password">
+                    </div>
+                </div>
+                <div class="form-grid form-grid-2">
+                    <div class="form-group">
+                        <label>Absendername</label>
+                        <input type="text" name="mail_from_name" value="<?= $h($settings['mail_from_name'] ?? '') ?>">
+                    </div>
+                    <div class="form-group">
+                        <label>Absender-E-Mail</label>
+                        <input type="email" name="mail_from_email" value="<?= $h($settings['mail_from_email'] ?? '') ?>">
+                    </div>
+                </div>
+                <button type="button" class="btn btn-secondary" id="btn-mail-test">Test-Mail senden</button>
+                <span id="mail-test-result" style="margin-left:.75rem;font-size:.8rem"></span>
+            </div>
+        </div>
+
     </div>
 
 </div>
 </form>
 
+<script>
+document.getElementById('btn-mail-test')?.addEventListener('click', function () {
+    var btn = this;
+    var result = document.getElementById('mail-test-result');
+    btn.disabled = true;
+    result.textContent = 'Sende…';
+    result.style.color = '';
+    fetch('/settings/mail-test', { method: 'POST', headers: { 'X-Requested-With': 'XMLHttpRequest' } })
+        .then(function (r) { return r.json(); })
+        .then(function (data) {
+            if (data.ok) {
+                result.textContent = '✓ Test-Mail erfolgreich gesendet.';
+                result.style.color = 'green';
+            } else {
+                result.textContent = '✗ ' + (data.error || 'Unbekannter Fehler');
+                result.style.color = 'red';
+            }
+        })
+        .catch(function () {
+            result.textContent = '✗ Netzwerkfehler';
+            result.style.color = 'red';
+        })
+        .finally(function () { btn.disabled = false; });
+});
+</script>
+
 <div style="display:grid;grid-template-columns:1fr 1fr;gap:1.5rem;margin-top:0">
     <div></div>
     <div>