Admin user roster; per-locale subject; SiteUser as From

- Admin preferences page can now subscribe existing webtrees users
  per tree, not just external addresses.
- Subject prefix is now configurable per locale (en/de), and the
  date in the subject is formatted via IntlDateFormatter in the
  recipient's locale.
- "From:" header now uses SiteUser (SMTP_FROM_NAME/SMTP_DISP_NAME)
  to match webtrees' own system-mail convention; the tree contact
  becomes the Reply-To.

src/Services/NewsletterDispatchService.php

@@ -15,6 +15,8 @@ use Fisharebest\Webtrees\Module\ModuleInterface;
 use Fisharebest\Webtrees\Registry;
 use Fisharebest\Webtrees\Services\TreeService;
 use Fisharebest\Webtrees\Services\UserService;
+use Fisharebest\Webtrees\Site;
+use Fisharebest\Webtrees\SiteUser;
 use Fisharebest\Webtrees\Tree;
 use Fisharebest\Webtrees\User;
 use Illuminate\Support\Collection;
@@ -22,6 +24,7 @@ use Intervention\Image\Drivers\Gd\Driver as GdDriver;
 use Intervention\Image\Drivers\Imagick\Driver as ImagickDriver;
 use Intervention\Image\Encoders\JpegEncoder;
 use Intervention\Image\ImageManager;
+use IntlDateFormatter;
 use Symfony\Component\Mailer\Exception\TransportExceptionInterface;
 use Symfony\Component\Mime\Exception\RfcComplianceException;
 use Throwable;
@@ -129,8 +132,17 @@ final class NewsletterDispatchService
             return sprintf('Tree "%s": no subscribers, skipped.', $tree->name());
         }
 
-        $from              = $this->siteContact($tree);
-        $original_locale   = I18N::languageTag();
+        // Match webtrees' own convention for system-generated email
+        // (registration confirmations, password resets, "new version
+        // available" notices): the From: header is the SiteUser
+        // (SMTP_FROM_NAME), while Reply-To: points at the family-tree
+        // contact person so replies still reach a human. If the site
+        // admin hasn't configured SMTP_FROM_NAME we fall back to the
+        // tree contact for From: too, otherwise the transport may
+        // reject the message for lacking a sender envelope.
+        $reply_to        = $this->siteContact($tree);
+        $from            = $this->siteFrom($reply_to);
+        $original_locale = I18N::languageTag();
         $groups            = $this->groupRecipientsByLanguage($recipients);
         $avatars           = $this->collectAvatars($birthdays, $anniversaries, $historical);
         $avatar_cids       = $this->avatarCids($avatars);
@@ -147,10 +159,11 @@ final class NewsletterDispatchService
             foreach ($groups as $lang => $group) {
                 I18N::init($lang);
 
-                $subject = Configuration::subjectPrefix($tree) . I18N::translate(
-                    'Family newsletter — %s',
-                    date('F j, Y', $now),
-                );
+                $subject = Configuration::subjectPrefixForLocale($tree, $lang)
+                    . I18N::translate(
+                        'Family newsletter — %s',
+                        $this->formatSubjectDate($now, $lang),
+                    );
 
                 // Render the email body per recipient — the relationship
                 // labels are personalised relative to whichever individual
@@ -188,7 +201,7 @@ final class NewsletterDispatchService
                     $text = $this->htmlToText($html);
 
                     try {
-                        if ($this->mailer->sendWithEmbeds($from, $recipient, $from, $subject, $text, $html, $recipient_avatars)) {
+                        if ($this->mailer->sendWithEmbeds($from, $recipient, $reply_to, $subject, $text, $html, $recipient_avatars)) {
                             $sent++;
                             // Per-user last-sent is stored only for real
                             // webtrees users (id > 0). External admin-
@@ -657,6 +670,22 @@ final class NewsletterDispatchService
         return $recipients;
     }
 
+    /**
+     * Resolve the From: identity, mirroring webtrees' own behaviour:
+     * the SMTP_FROM_NAME / SMTP_DISP_NAME site preferences if set,
+     * otherwise the tree contact user (so the transport always has
+     * a usable envelope sender). This is the address recipients see
+     * in their mail client, not the one their replies go to.
+     */
+    private function siteFrom(UserInterface $fallback): UserInterface
+    {
+        if (trim(Site::getPreference('SMTP_FROM_NAME')) !== '') {
+            return new SiteUser();
+        }
+
+        return $fallback;
+    }
+
     /**
      * Pick a sender identity. Fall back to a synthetic UserInterface if
      * the site has no contact user configured for this tree.
@@ -692,6 +721,34 @@ final class NewsletterDispatchService
         return new ExtraRecipient($address, self::FROM_NAME);
     }
 
+    /**
+     * Format the issue date for the email subject in the recipient's
+     * locale: "15. Mai 2026" for de, "May 15, 2026" for en-US. Falls
+     * back to the English date() format if ext-intl is unavailable —
+     * webtrees lists intl as required so this should not happen in
+     * practice, but we don't want to fatal a dispatch over it.
+     */
+    private function formatSubjectDate(int $timestamp, string $language): string
+    {
+        if (class_exists(IntlDateFormatter::class)) {
+            $formatter = IntlDateFormatter::create(
+                str_replace('-', '_', $language),
+                IntlDateFormatter::LONG,
+                IntlDateFormatter::NONE,
+            );
+
+            if ($formatter instanceof IntlDateFormatter) {
+                $formatted = $formatter->format($timestamp);
+
+                if (is_string($formatted) && $formatted !== '') {
+                    return $formatted;
+                }
+            }
+        }
+
+        return date('F j, Y', $timestamp);
+    }
+
     private function htmlToText(string $html): string
     {
         $without_tags = preg_replace('/<\s*br\s*\/?>/i', "\n", $html) ?? $html;