diff --git a/core/admin/mailu/models.py b/core/admin/mailu/models.py
index 901054a8..48f7b91e 100644
--- a/core/admin/mailu/models.py
+++ b/core/admin/mailu/models.py
@@ -60,6 +60,7 @@ class Domain(Base):
     max_users = db.Column(db.Integer, nullable=False, default=0)
     max_aliases = db.Column(db.Integer, nullable=False, default=0)
     max_quota_bytes = db.Column(db.Integer(), nullable=False, default=0)
+    signup_enabled = db.Column(db.Boolean(), nullable=False, default=False)
 
     @property
     def dkim_key(self):
diff --git a/core/admin/mailu/ui/forms.py b/core/admin/mailu/ui/forms.py
index 451db811..1d27141d 100644
--- a/core/admin/mailu/ui/forms.py
+++ b/core/admin/mailu/ui/forms.py
@@ -47,6 +47,7 @@ class DomainForm(flask_wtf.FlaskForm):
     max_users = fields_.IntegerField(_('Maximum user count'), default=10)
     max_aliases = fields_.IntegerField(_('Maximum alias count'), default=10)
     max_quota_bytes = fields_.IntegerSliderField(_('Maximum user quota'), default=0)
+    signup_enabled = fields.BooleanField(_('Enable sign-up'), default=False)
     comment = fields.StringField(_('Comment'))
     submit = fields.SubmitField(_('Create'))
 
@@ -74,6 +75,13 @@ class UserForm(flask_wtf.FlaskForm):
     submit = fields.SubmitField(_('Save'))
 
 
+class UserSignupForm(flask_wtf.FlaskForm):
+    localpart = fields.StringField(_('Email address'))
+    pw = fields.PasswordField(_('Password'), [validators.DataRequired()])
+    pw2 = fields.PasswordField(_('Confirm password'), [validators.EqualTo('pw')])
+    submit = fields.SubmitField(_('Sign up'))
+
+
 class UserSettingsForm(flask_wtf.FlaskForm):
     displayed_name = fields.StringField(_('Displayed name'))
     spam_enabled = fields.BooleanField(_('Enable spam filter'))
diff --git a/core/admin/mailu/ui/templates/sidebar.html b/core/admin/mailu/ui/templates/sidebar.html
index 22bbfce5..d107c15f 100644
--- a/core/admin/mailu/ui/templates/sidebar.html
+++ b/core/admin/mailu/ui/templates/sidebar.html
@@ -100,10 +100,17 @@
     </li>
     {% else %}
     <li>
-      <a href="#">
+      <a href="{{ url_for('.login') }}">
         <i class="fa fa-sign-in"></i> <span>{% trans %}Sign in{% endtrans %}</span>
       </a>
     </li>
+    {% if signup_domains %}
+    <li>
+      <a href="{{ url_for('.user_signup') }}">
+        <i class="fa fa-user-plus"></i> <span>{% trans %}Sign up{% endtrans %}</span>
+      </a>
+    </li>
+    {% endif %}
     {% endif %}
   </ul>
 </section>
diff --git a/core/admin/mailu/ui/templates/user/signup.html b/core/admin/mailu/ui/templates/user/signup.html
new file mode 100644
index 00000000..eccd9f67
--- /dev/null
+++ b/core/admin/mailu/ui/templates/user/signup.html
@@ -0,0 +1,20 @@
+{% extends "base.html" %}
+
+{% block title %}
+{% trans %}Sign up{% endtrans %}
+{% endblock %}
+
+{% block subtitle %}
+{{ domain }}
+{% endblock %}
+
+{% block content %}
+<form class="form" method="post" role="form">
+  {{ form.hidden_tag() }}
+  {% 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.submit) }}
+  {% endcall %}
+</form>
+{% endblock %}
diff --git a/core/admin/mailu/ui/templates/user/signup_domain.html b/core/admin/mailu/ui/templates/user/signup_domain.html
new file mode 100644
index 00000000..d5df77dd
--- /dev/null
+++ b/core/admin/mailu/ui/templates/user/signup_domain.html
@@ -0,0 +1,26 @@
+{% extends "base.html" %}
+
+{% block title %}
+{% trans %}Sign up{% endtrans %}
+{% endblock %}
+
+{% block subtitle %}
+{% trans %}pick a domain for the new account{% endtrans %}
+{% endblock %}
+
+{% block content %}
+{% call macros.table() %}
+<tr>
+  <th>{% trans %}Domain{% endtrans %}</th>
+  <th>{% trans %}Available slots{% endtrans %}</th>
+  <th>{% trans %}Quota{% endtrans %}</th>
+</tr>
+{% for domain_name, domain in available_domains.items() %}
+<tr>
+  <td><a href="{{ url_for('.user_signup', domain_name=domain_name) }}">{{ domain_name }}</a></td>
+  <td>{{ domain.max_users - domain.users if domain.max_users else '∞' }}</td>
+  <td>{{ domain.max_quota_bytes or config['DEFAULT_QUOTA'] | filesizeformat }}</td>
+</tr>
+{% endfor %}
+{% endcall %}
+{% endblock %}
diff --git a/core/admin/mailu/ui/views/users.py b/core/admin/mailu/ui/views/users.py
index 34f7be8f..77499699 100644
--- a/core/admin/mailu/ui/views/users.py
+++ b/core/admin/mailu/ui/views/users.py
@@ -153,3 +153,35 @@ def user_reply(user_email):
             return flask.redirect(
                 flask.url_for('.user_list', domain_name=user.domain.name))
     return flask.render_template('user/reply.html', form=form, user=user)
+
+
+@ui.route('/user/signup', methods=['GET', 'POST'])
+@ui.route('/user/signup/<domain_name>', methods=['GET', 'POST'])
+def user_signup(domain_name=None):
+    available_domains = {
+        domain.name: domain
+        for domain in models.Domain.query.filter_by(signup_enabled=True).all()
+        if not domain.max_users or len(domain.users) < domain.max_users
+    }
+    if not available_domains:
+        flask.flash('No domain available for registration')
+    if not domain_name:
+        return flask.render_template('user/signup_domain.html',
+            available_domains=available_domains)
+    domain = available_domains.get(domain_name) or flask.abort(404)
+    quota_bytes = min(config['DEFAULT_QUOTA'], domain.max_quota_bytes)
+    form = forms.UserSignupForm()
+    if form.validate_on_submit():
+        if domain.has_email(form.localpart.data):
+            flask.flash('Email is already used', 'error')
+        else:
+            user = models.User(domain=domain)
+            form.populate_obj(user)
+            user.set_password(form.pw.data)
+            user.quota_bytes = quota_bytes
+            db.session.add(user)
+            db.session.commit()
+            user.send_welcome()
+            flask.flash('Successfully signed up %s' % user)
+            return flask.redirect(flask.url_for('.index'))
+    return flask.render_template('user/signup.html', domain=domain, form=form)