💄(mail) improve mailbox creation email

Remove useless icons, modify text
and improve displaying.

src/backend/debug/urls.py

@@ -4,6 +4,7 @@ from django.urls import path
 
 from .views import (
     DebugViewHtml,
+    DebugViewNewMailboxHtml,
     DebugViewTxt,
 )
 
@@ -18,4 +19,9 @@ urlpatterns = [
         DebugViewTxt.as_view(),
         name="debug.mail.invitation_txt",
     ),
+    path(
+        "__debug__/mail/new_mailbox_html",
+        DebugViewNewMailboxHtml.as_view(),
+        name="debug.mail.new_mailbox_html",
+    ),
 ]

src/backend/debug/views.py

@@ -25,3 +25,17 @@ class DebugViewTxt(DebugBaseView):
     """Debug View for Text Email Layout"""
 
     template_name = "mail/text/invitation.txt"
+
+
+class DebugViewNewMailboxHtml(DebugBaseView):
+    """Debug view for new mailbox email layout"""
+
+    template_name = "mail/html/new_mailbox.html"
+
+    def get_context_data(self, **kwargs):
+        context = super().get_context_data(**kwargs)
+        context["mailbox_data"] = {
+            "email": "john.doe@example.com",
+            "password": "6HGVAsjoog_v",
+        }
+        return context