diff --git a/boards/admin.py b/boards/admin.py
--- a/boards/admin.py
+++ b/boards/admin.py
@@ -8,13 +8,14 @@ from boards.models import Post, Tag, Ban
 @admin.register(Post)
 class PostAdmin(admin.ModelAdmin):
 
-    list_display = ('id', 'title', 'text', 'poster_ip', 'linked_images', 'linked_global_id')
+    list_display = ('id', 'title', 'text', 'poster_ip', 'linked_images',
+            'foreign')
     list_filter = ('pub_time',)
     search_fields = ('id', 'title', 'text', 'poster_ip')
     exclude = ('referenced_posts', 'refmap', 'images', 'global_id')
     readonly_fields = ('poster_ip', 'threads', 'thread', 'linked_images',
             'attachments', 'uid', 'url', 'pub_time', 'opening', 'linked_global_id',
-            'version')
+            'version', 'foreign')
 
     def ban_poster(self, request, queryset):
         bans = 0
@@ -61,6 +62,10 @@ class PostAdmin(admin.ModelAdmin):
         obj.save()
         obj.clear_cache()
 
+    def foreign(self, obj: Post):
+        return obj is not None and obj.global_id is not None and\
+                not obj.global_id.is_local()
+
     actions = ['ban_poster', 'ban_with_hiding']