diff --git a/website_event_attendee_signup/data/mail_template_data.xml b/website_event_attendee_signup/data/mail_template_data.xml
index 585fc71..5f46611 100644
--- a/website_event_attendee_signup/data/mail_template_data.xml
+++ b/website_event_attendee_signup/data/mail_template_data.xml
@@ -2,34 +2,42 @@
 <odoo noupdate="1">
     <record id="email_template_signup" model="mail.template">
         <field name="name">Event: Signup</field>
-        <!--<field name="email_from">${(object.partner_id.email or '')|safe}</field>-->
+        <field
+            name="email_from"
+        >{{ (object.event_id.organizer_id.email_formatted or object.event_id.user_id.email_formatted or '') }}</field>
         <field name="subject">Welcome to our Portal!</field>
-        <field name="partner_to">${object.attendee_partner_id.id}</field>
+        <field
+            name="email_to"
+        >{{object.attendee_partner_id.email or object.partner_id.email}}</field>
         <field name="model_id" ref="event.model_event_registration" />
         <field name="auto_delete" eval="True" />
-        <field name="lang">${object.attendee_partner_id.lang}</field>
         <field
-            name="body_html"
-        ><![CDATA[
-
+            name="lang"
+        >{{object.attendee_partner_id.lang or object.event_id.lang or object.partner_id.lang}}</field>
+        <field name="body_html" type="html">
         <p>
-            Hello ${object.attendee_partner_id.name},<br />
+            Hello <t t-out="object.attendee_partner_id.name" />,<br />
 
-            You was registered as attendee of ${object.event_id.name}.
+            You was registered as attendee of <t t-out="object.event_id.name" />.
 
-            % if object.attendee_partner_id.signup_token:
+            <t t-if="object.attendee_partner_id.signup_token">
                 Use the link below to sing-up on portal to access your event dashboard:
-                    <div style="padding:0px;width:600px;margin:auto;background: #FFFFFF repeat top /100%;color:#777777">
+                    <div
+                        style="padding:0px;width:600px;margin:auto;background: #FFFFFF repeat top /100%;color:#777777"
+                    >
                         <div style="text-align: center; margin-top: 16px;">
-                             <a href="${object.attendee_partner_id.signup_url}" style="padding: 5px 10px; font-size: 12px; line-height: 18px; color: #FFFFFF; border-color:#875A7B; text-decoration: none; display: inline-block; margin-bottom: 0px; font-weight: 400; text-align: center; vertical-align: middle; cursor: pointer; white-space: nowrap; background-image: none; background-color: #875A7B; border: 1px solid #875A7B; border-radius:3px">Accept invitation to portal</a>
+                             <a
+                                t-att-href="object.attendee_partner_id.signup_url"
+                                style="padding: 5px 10px; font-size: 12px; line-height: 18px; color: #FFFFFF; border-color:#875A7B; text-decoration: none; display: inline-block; margin-bottom: 0px; font-weight: 400; text-align: center; vertical-align: middle; cursor: pointer; white-space: nowrap; background-image: none; background-color: #875A7B; border: 1px solid #875A7B; border-radius:3px"
+                            >Accept invitation to portal</a>
                         </div>
                     </div>
-            % endif
+            </t>
         </p>
         <p>
         </p>
         <p>Best regards,</p>
 
-        ]]></field>
+        </field>
     </record>
 </odoo>
diff --git a/website_event_attendee_signup/models/event_registration.py b/website_event_attendee_signup/models/event_registration.py
index 8a47950..318cabf 100644
--- a/website_event_attendee_signup/models/event_registration.py
+++ b/website_event_attendee_signup/models/event_registration.py
@@ -1,24 +1,41 @@
-from odoo import api, models
+from odoo import models
 
 
 class EventRegistration(models.Model):
     _inherit = "event.registration"
 
-    @api.model
-    def create(self, vals):
-        res = super().create(vals)
-
-        if res.event_id.attendee_signup and res.attendee_partner_id:
-            login = res.attendee_partner_id.email
-            user = self.env["res.users"].search([("login", "=ilike", login)])
-            if not user:
-                user = (
-                    self.env["res.users"]
-                    .sudo()
-                    ._signup_create_user(
-                        {"login": login, "partner_id": res.attendee_partner_id.id}
-                    )
-                )
-                user.partner_id.signup_prepare()
-
-        return res
+    def _update_attendee_partner_id(self, vals):
+        vals = super()._update_attendee_partner_id(vals)
+        if not vals.get("attendee_partner_id"):
+            return vals
+
+        if not vals.get("event_id"):
+            return vals
+
+        Partner = self.env["res.partner"].sudo()
+        Users = self.env["res.users"].sudo()
+        Events = self.env["event.event"].sudo()
+
+        event = Events.browse(vals["event_id"])
+        if not event.attendee_signup:
+            return vals
+
+        attendee_partner = Partner.browse(vals["attendee_partner_id"])
+        if attendee_partner.user_ids:
+            # already has user
+            return vals
+
+        login = attendee_partner.email
+        if not login:
+            return vals
+
+        user = Users.search([("login", "=ilike", login)])
+        if user:
+            # already has user with given address
+            return vals
+
+        user = Users._signup_create_user(
+            {"login": login, "partner_id": attendee_partner.id}
+        )
+        user.partner_id.signup_prepare()
+        return vals