diff --git a/core/admin/mailu/__init__.py b/core/admin/mailu/__init__.py
index ef98cf9e..e32d2e7d 100644
--- a/core/admin/mailu/__init__.py
+++ b/core/admin/mailu/__init__.py
@@ -52,6 +52,8 @@ default_config = {
     'WEBSITE': 'https://mailu.io',
     'WEB_ADMIN': '/admin',
     'WEB_WEBMAIL': '/webmail',
+    'RECAPTCHA_PUBLIC_KEY': '',
+    'RECAPTCHA_PRIVATE_KEY': '',
     # Advanced settings
     'PASSWORD_SCHEME': 'SHA512-CRYPT',
     # Host settings
diff --git a/core/admin/mailu/ui/forms.py b/core/admin/mailu/ui/forms.py
index 3c476c67..80d73fbe 100644
--- a/core/admin/mailu/ui/forms.py
+++ b/core/admin/mailu/ui/forms.py
@@ -79,6 +79,7 @@ class UserSignupForm(flask_wtf.FlaskForm):
     localpart = fields.StringField(_('Email address'), [validators.DataRequired(), validators.Regexp("^[a-zA-Z0-9.!#$%&’*+/=?^_`{|}~-]+$")])
     pw = fields.PasswordField(_('Password'), [validators.DataRequired()])
     pw2 = fields.PasswordField(_('Confirm password'), [validators.EqualTo('pw')])
+    captcha = flask_wtf.RecaptchaField()
     submit = fields.SubmitField(_('Sign up'))
 
 
diff --git a/core/admin/mailu/ui/templates/user/signup.html b/core/admin/mailu/ui/templates/user/signup.html
index eccd9f67..59c1a988 100644
--- a/core/admin/mailu/ui/templates/user/signup.html
+++ b/core/admin/mailu/ui/templates/user/signup.html
@@ -14,6 +14,7 @@
   {% call macros.box() %}
   {{ macros.form_field(form.localpart, append='<span class="input-group-addon">@'+domain.name+'</span>') }}
   {{ macros.form_fields((form.pw, form.pw2)) }}
+  {{ macros.form_field(form.captcha) }}
   {{ macros.form_field(form.submit) }}
   {% endcall %}
 </form>
diff --git a/docs/compose/.env b/docs/compose/.env
index 6f330b64..e5c67129 100644
--- a/docs/compose/.env
+++ b/docs/compose/.env
@@ -103,6 +103,10 @@ SITENAME=Mailu
 # Linked Website URL
 WEBSITE=https://mailu.io
 
+# Registration reCaptcha settings (warning, this has some privacy impact)
+# RECAPTCHA_PUBLIC_KEY=
+# RECAPTCHA_PRIVATE_KEY=
+
 ###################################
 # Advanced settings
 ###################################