diff --git a/app/controllers/admin/settings/others_controller.rb b/app/controllers/admin/settings/others_controller.rb
new file mode 100644
index 00000000000..113d0c84ff1
--- /dev/null
+++ b/app/controllers/admin/settings/others_controller.rb
@@ -0,0 +1,9 @@
+# frozen_string_literal: true
+
+class Admin::Settings::OthersController < Admin::SettingsController
+  private
+
+  def after_update_redirect_path
+    admin_settings_others_path
+  end
+end
diff --git a/app/lib/activitypub/activity/create.rb b/app/lib/activitypub/activity/create.rb
index 85195f4c395..b9f78feb141 100644
--- a/app/lib/activitypub/activity/create.rb
+++ b/app/lib/activitypub/activity/create.rb
@@ -47,7 +47,7 @@ class ActivityPub::Activity::Create < ActivityPub::Activity
   end
 
   def create_status
-    return reject_payload! if unsupported_object_type? || non_matching_uri_hosts?(@account.uri, object_uri) || tombstone_exists? || !related_to_local_activity?
+    return reject_payload! if unsupported_object_type? || non_matching_uri_hosts?(@account.uri, object_uri) || tombstone_exists? || !related_to_local_activity? || reject_pattern?
 
     with_redis_lock("create:#{object_uri}") do
       return if delete_arrived_first?(object_uri) || poll_vote?
@@ -413,6 +413,10 @@ class ActivityPub::Activity::Create < ActivityPub::Activity
     Tombstone.exists?(uri: object_uri)
   end
 
+  def reject_pattern?
+    Setting.reject_pattern.present? && @object['content']&.match?(Setting.reject_pattern)
+  end
+
   def forward_for_reply
     return unless @status.distributable? && @json['signature'].present? && reply_to_local?
 
diff --git a/app/models/form/admin_settings.rb b/app/models/form/admin_settings.rb
index cb37a522174..69907d7fe2f 100644
--- a/app/models/form/admin_settings.rb
+++ b/app/models/form/admin_settings.rb
@@ -37,6 +37,7 @@ class Form::AdminSettings
     status_page_url
     captcha_enabled
     authorized_fetch
+    reject_pattern
   ).freeze
 
   INTEGER_KEYS = %i(
@@ -79,6 +80,7 @@ class Form::AdminSettings
   validates :show_domain_blocks_rationale, inclusion: { in: %w(disabled users all) }, if: -> { defined?(@show_domain_blocks_rationale) }
   validates :media_cache_retention_period, :content_cache_retention_period, :backups_retention_period, numericality: { only_integer: true }, allow_blank: true, if: -> { defined?(@media_cache_retention_period) || defined?(@content_cache_retention_period) || defined?(@backups_retention_period) }
   validates :site_short_description, length: { maximum: 200 }, if: -> { defined?(@site_short_description) }
+  validates :reject_pattern, regexp_syntax: true, if: -> { defined?(@reject_pattern) }
   validates :status_page_url, url: true, allow_blank: true
   validate :validate_site_uploads
 
diff --git a/app/validators/regexp_syntax_validator.rb b/app/validators/regexp_syntax_validator.rb
new file mode 100644
index 00000000000..dd8dc80c9fe
--- /dev/null
+++ b/app/validators/regexp_syntax_validator.rb
@@ -0,0 +1,11 @@
+# frozen_string_literal: true
+
+class RegexpSyntaxValidator < ActiveModel::EachValidator
+  def validate_each(record, attribute, value)
+    return if value.blank?
+
+    Regexp.compile(value)
+  rescue RegexpError => e
+    record.errors.add(attribute, I18n.t('applications.invalid_regexp', message: e.message))
+  end
+end
diff --git a/app/views/admin/settings/others/show.html.haml b/app/views/admin/settings/others/show.html.haml
new file mode 100644
index 00000000000..06dcf2bf8b0
--- /dev/null
+++ b/app/views/admin/settings/others/show.html.haml
@@ -0,0 +1,19 @@
+- content_for :page_title do
+  = t('admin.settings.others.title')
+
+- content_for :heading do
+  %h2= t('admin.settings.title')
+  = render partial: 'admin/settings/shared/links'
+
+= simple_form_for @admin_settings, url: admin_settings_others_path, html: { method: :patch } do |f|
+  = render 'shared/error_messages', object: @admin_settings
+
+  %p.lead= t('admin.settings.others.preamble')
+
+  %h4= t('admin.settings.others.activitypub')
+
+  .fields-group
+    = f.input :reject_pattern, wrapper: :with_block_label, as: :text, label: t('admin.settings.reject_pattern.title'), hint: t('admin.settings.reject_pattern.desc_html'), input_html: { rows: 8 }
+
+  .actions
+    = f.button :button, t('generic.save_changes'), type: :submit
diff --git a/app/views/admin/settings/shared/_links.html.haml b/app/views/admin/settings/shared/_links.html.haml
index 8b0678d4c91..ab2965538f9 100644
--- a/app/views/admin/settings/shared/_links.html.haml
+++ b/app/views/admin/settings/shared/_links.html.haml
@@ -7,3 +7,4 @@
       primary.item :discovery, safe_join([fa_icon('search fw'), t('admin.settings.discovery.title')]), admin_settings_discovery_path
       primary.item :content_retention, safe_join([fa_icon('history fw'), t('admin.settings.content_retention.title')]), admin_settings_content_retention_path
       primary.item :appearance, safe_join([fa_icon('desktop fw'), t('admin.settings.appearance.title')]), admin_settings_appearance_path
+      primary.item :others, safe_join([fa_icon('cogs fw'), t('admin.settings.others.title')]), admin_settings_others_path
diff --git a/config/locales/en.yml b/config/locales/en.yml
index 446d06f0d1f..095d53352e4 100644
--- a/config/locales/en.yml
+++ b/config/locales/en.yml
@@ -770,6 +770,10 @@ en:
         all: To everyone
         disabled: To no one
         users: To logged-in local users
+      others:
+        activitypub: ActivityPub
+        preamble: Other settings, including customizing behavior
+        title: Other settings
       registrations:
         moderation_recommandation: Please make sure you have an adequate and reactive moderation team before you open registrations to everyone!
         preamble: Control who can create an account on your server.
@@ -780,6 +784,9 @@ en:
           none: Nobody can sign up
           open: Anyone can sign up
         warning_hint: We recommend using “Approval required for sign up” unless you are confident your moderation team can handle spam and malicious registrations in a timely fashion.
+      reject_pattern:
+        desc_html: Set a regular expression pattern to inspect Create Activity content, and refuse Activity if you match
+        title: Reject Pattern
       security:
         authorized_fetch: Require authentication from federated servers
         authorized_fetch_hint: Requiring authentication from federated servers enables stricter enforcement of both user-level and server-level blocks. However, this comes at the cost of a performance penalty, reduces the reach of your replies, and may introduce compatibility issues with some federated services. In addition, this will not prevent dedicated actors from fetching your public posts and accounts.
@@ -1038,6 +1045,7 @@ en:
   applications:
     created: Application successfully created
     destroyed: Application successfully deleted
+    invalid_regexp: 'The provided Regexp is invalid: %{message}'
     logout: Logout
     regenerate_token: Regenerate access token
     token_regenerated: Access token successfully regenerated
diff --git a/config/routes/admin.rb b/config/routes/admin.rb
index 207cb0580dc..6b1f0e1a166 100644
--- a/config/routes/admin.rb
+++ b/config/routes/admin.rb
@@ -50,6 +50,7 @@ namespace :admin do
     resource :about, only: [:show, :update], controller: 'about'
     resource :appearance, only: [:show, :update], controller: 'appearance'
     resource :discovery, only: [:show, :update], controller: 'discovery'
+    resource :others, only: [:show, :update], controller: 'others'
   end
 
   resources :site_uploads, only: [:destroy]
diff --git a/config/settings.yml b/config/settings.yml
index 297bf0281d0..599ba46a667 100644
--- a/config/settings.yml
+++ b/config/settings.yml
@@ -38,6 +38,7 @@ defaults: &defaults
   require_invite_text: false
   backups_retention_period: 7
   captcha_enabled: false
+  reject_pattern: ''
 
 development:
   <<: *defaults