diff --git a/jdav_web/mailer/admin.py b/jdav_web/mailer/admin.py
index e59a3b5..9c1af2b 100644
--- a/jdav_web/mailer/admin.py
+++ b/jdav_web/mailer/admin.py
@@ -22,7 +22,8 @@ class AttachmentInline(CommonAdminInlineMixin, admin.TabularInline):
 
 
 class EmailAddressAdmin(FilteredMemberFieldMixin, admin.ModelAdmin):
-    list_display = ('email', )
+    list_display = ('email', 'internal_only')
+    fields = ('name', 'to_members', 'to_groups', 'internal_only')
     #formfield_overrides = {
     #    models.ManyToManyField: {'widget': forms.CheckboxSelectMultiple},
     #    models.ForeignKey: {'widget': apply_select2(forms.Select)}
diff --git a/jdav_web/mailer/locale/de/LC_MESSAGES/django.po b/jdav_web/mailer/locale/de/LC_MESSAGES/django.po
index afa3394..c0ef976 100644
--- a/jdav_web/mailer/locale/de/LC_MESSAGES/django.po
+++ b/jdav_web/mailer/locale/de/LC_MESSAGES/django.po
@@ -8,7 +8,7 @@ msgid ""
 msgstr ""
 "Project-Id-Version: PACKAGE VERSION\n"
 "Report-Msgid-Bugs-To: \n"
-"POT-Creation-Date: 2024-12-01 16:56+0100\n"
+"POT-Creation-Date: 2024-12-01 18:49+0100\n"
 "PO-Revision-Date: YEAR-MO-DA HO:MI+ZONE\n"
 "Last-Translator: FULL NAME <EMAIL@ADDRESS>\n"
 "Language-Team: LANGUAGE <LL@li.org>\n"
@@ -18,19 +18,19 @@ msgstr ""
 "Content-Transfer-Encoding: 8bit\n"
 "Plural-Forms: nplurals=2; plural=(n != 1);\n"
 
-#: mailer/admin.py:68
+#: mailer/admin.py:69
 msgid "Send message"
 msgstr "Nachricht verschicken"
 
-#: mailer/admin.py:98
+#: mailer/admin.py:99
 msgid "Failed to send message"
 msgstr "Fehler beim Senden der Email"
 
-#: mailer/admin.py:100
+#: mailer/admin.py:101
 msgid "Failed to send some messages"
 msgstr "Fehler beim Senden der Emails"
 
-#: mailer/admin.py:102
+#: mailer/admin.py:103
 msgid "Successfully sent message"
 msgstr "Email wurde erfolgreich verschickt"
 
@@ -59,11 +59,21 @@ msgstr "Weiterleitung an Teilnehmer*innen"
 msgid "Forward to group"
 msgstr "Weiterleitung an Gruppe"
 
+#: mailer/models.py:31
+msgid "Restrict to internal email addresses"
+msgstr "Weiterleitung nur von internen E-Mail Adressen erlaubt"
+
 #: mailer/models.py:32
+msgid "Only allow forwarding to this e-mail address from the internal domain."
+msgstr ""
+"Leite nur E-Mails weiter, die von ...@alpenverein-heidelberg.de verschickt "
+"wurden. "
+
+#: mailer/models.py:35
 msgid "Allowed sender"
 msgstr "Erlaubte Absender:innen"
 
-#: mailer/models.py:33
+#: mailer/models.py:36
 msgid ""
 "Only forward e-mails of members of selected groups. Leave empty to allow all "
 "senders."
@@ -71,100 +81,100 @@ msgstr ""
 "Leite nur E-Mails von Mitgliedern dieser Gruppen weiter. Lasse dieses Feld "
 "frei, um alle Absender*innen zu erlauben."
 
-#: mailer/models.py:51
+#: mailer/models.py:54
 msgid "email address"
 msgstr "Email-Adresse"
 
-#: mailer/models.py:52
+#: mailer/models.py:55
 msgid "email addresses"
 msgstr "Email-Adressen"
 
-#: mailer/models.py:65
+#: mailer/models.py:68
 msgid "Either a group or at least one member is required as forward recipient."
 msgstr ""
 "Es muss entweder eine Gruppe oder mindestens ein*e Teilnehmer*in als "
 "Empfänger*in ausgewählt werden."
 
-#: mailer/models.py:73
+#: mailer/models.py:76
 msgid "subject"
 msgstr "Betreff"
 
-#: mailer/models.py:74
+#: mailer/models.py:77
 msgid "content"
 msgstr "Inhalt"
 
-#: mailer/models.py:76
+#: mailer/models.py:79
 msgid "to group"
 msgstr "An Gruppe"
 
-#: mailer/models.py:79
+#: mailer/models.py:82
 msgid "to freizeit"
 msgstr "An Ausfahrt"
 
-#: mailer/models.py:84
+#: mailer/models.py:87
 msgid "to notes list"
 msgstr "An Notizliste"
 
-#: mailer/models.py:89
+#: mailer/models.py:92
 msgid "to member"
 msgstr "An Teilnehmer*innen"
 
-#: mailer/models.py:92
+#: mailer/models.py:95
 msgid "reply to participant"
 msgstr "Antwort an Teilnehmer*innen"
 
-#: mailer/models.py:96
+#: mailer/models.py:99
 msgid "reply to custom email address"
 msgstr "Antwort an Email-Adresse"
 
-#: mailer/models.py:99
+#: mailer/models.py:102
 msgid "sent"
 msgstr "Gesendet"
 
-#: mailer/models.py:100
+#: mailer/models.py:103
 msgid "Created by"
 msgstr "Erstellt von"
 
-#: mailer/models.py:118
+#: mailer/models.py:121
 msgid "Some other members"
 msgstr "Andere Teilnehmer*innen"
 
-#: mailer/models.py:120
+#: mailer/models.py:123
 msgid "recipients"
 msgstr "Empfänger"
 
-#: mailer/models.py:183
+#: mailer/models.py:186
 msgid "message"
 msgstr "Nachricht"
 
-#: mailer/models.py:184
+#: mailer/models.py:187
 msgid "messages"
 msgstr "Nachrichten"
 
-#: mailer/models.py:186
+#: mailer/models.py:189
 msgid "Can submit mails"
 msgstr "Kann Mails verschicken"
 
-#: mailer/models.py:207
+#: mailer/models.py:210
 msgid ""
 "Either a group, a memberlist or at least one member is required as recipient"
 msgstr ""
 "Es muss entweder eine Gruppe, eine Teilnehmer*innenliste oder mindestens "
 "ein*e Teilnehmer*in als Empfänger*in ausgewählt werden."
 
-#: mailer/models.py:214
+#: mailer/models.py:217
 msgid "file"
 msgstr "Datei"
 
-#: mailer/models.py:219
+#: mailer/models.py:222
 msgid "Empty"
 msgstr "Leer"
 
-#: mailer/models.py:222
+#: mailer/models.py:225
 msgid "attachment"
 msgstr "Anhang"
 
-#: mailer/models.py:223
+#: mailer/models.py:226
 msgid "attachments"
 msgstr "Anhänge"
 
diff --git a/jdav_web/mailer/migrations/0007_emailaddress_internal_only.py b/jdav_web/mailer/migrations/0007_emailaddress_internal_only.py
new file mode 100644
index 0000000..6bc75ce
--- /dev/null
+++ b/jdav_web/mailer/migrations/0007_emailaddress_internal_only.py
@@ -0,0 +1,18 @@
+# Generated by Django 4.0.1 on 2024-12-01 17:45
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('mailer', '0006_emailaddress_allowed_senders'),
+    ]
+
+    operations = [
+        migrations.AddField(
+            model_name='emailaddress',
+            name='internal_only',
+            field=models.BooleanField(default=False, help_text='Only allow forwarding to this e-mail address from the internal domain.', verbose_name='Restrict to internal email addresses'),
+        ),
+    ]
diff --git a/jdav_web/mailer/models.py b/jdav_web/mailer/models.py
index 96551e3..3e08d2f 100644
--- a/jdav_web/mailer/models.py
+++ b/jdav_web/mailer/models.py
@@ -28,6 +28,9 @@ class EmailAddress(models.Model):
     to_groups = models.ManyToManyField('members.Group',
                                        verbose_name=_('Forward to group'),
                                        blank=True)
+    internal_only = models.BooleanField(verbose_name=_('Restrict to internal email addresses'),
+                                        help_text=_('Only allow forwarding to this e-mail address from the internal domain.'),
+                                        default=False)
     allowed_senders = models.ManyToManyField('members.Group',
                                              verbose_name=_('Allowed sender'),
                                              help_text=_('Only forward e-mails of members of selected groups. Leave empty to allow all senders.'),