diff --git a/src/pretix/base/services/mail.py b/src/pretix/base/services/mail.py
index d04f45f256..15b09867b8 100644
--- a/src/pretix/base/services/mail.py
+++ b/src/pretix/base/services/mail.py
@@ -321,7 +321,7 @@ def mail(email: Union[str, Sequence[str]], subject: str, template: Union[str, La
             body_plain=body_plain,
             body_html=body_html,
             sender=sender,
-            headers=headers,
+            headers=headers or {},
             should_attach_tickets=attach_tickets,
             should_attach_ical=attach_ical,
             should_attach_other_files=attach_other_files or [],
@@ -763,7 +763,7 @@ def mail_send(to: List[str], subject: str, body: str, html: Optional[str], sende
         body_plain=body,
         body_html=html,
         sender=sender,
-        headers=headers,
+        headers=headers or {},
         should_attach_tickets=attach_tickets,
         should_attach_ical=attach_ical,
         should_attach_other_files=attach_other_files or [],
diff --git a/src/pretix/static/pretixcontrol/js/ui/editor.js b/src/pretix/static/pretixcontrol/js/ui/editor.js
index cce09a7386..2c8c92c719 100644
--- a/src/pretix/static/pretixcontrol/js/ui/editor.js
+++ b/src/pretix/static/pretixcontrol/js/ui/editor.js
@@ -674,10 +674,11 @@ var editor = {
             $("#toolbox").find("button[data-action=middle]").toggleClass('active', o.verticalAlign === 'middle');
             $("#toolbox").find("button[data-action=bottom]").toggleClass('active', o.verticalAlign === 'bottom');
 
+            console.log("_update_toolbox_values", o.scaleY, o.scaleX)
             if (o.scaleY !== 1 || o.scaleX !== 1) {
                 o.set({
-                    height: o.height * o.scaleY,
-                    width: o.width * o.scaleX,
+                    height: Math.max(o.height * o.scaleY, editor._mm2px(10.01)),
+                    width: Math.max(o.width * o.scaleX, editor._mm2px(10.01)),
                     scaleX: 1,
                     scaleY: 1
                 });