update "reply must from mailbox" email wording

email_handler.py

@@ -919,7 +919,7 @@ def handle_unknown_mailbox(envelope, msg, reply_email: str, user: User, alias: A
         user,
         ALERT_REVERSE_ALIAS_UNKNOWN_MAILBOX,
         user.email,
-        f"Reply from your alias {alias.email} only works from your mailbox",
+        f"Attempt to use your alias {alias.email} from {envelope.mail_from}",
         render(
             "transactional/reply-must-use-personal-email.txt",
             name=user.name,

templates/emails/transactional/reply-must-use-personal-email.html

@@ -15,7 +15,9 @@
   {% endcall %}
 
   {% call text() %}
-    Indeed only you can send emails on behalf of your alias.
+    This is to protect against "email spoofing", i.e. someone else sending emails from your mailbox. <br>
+    Indeed only you can send emails on behalf of your alias. <br>
+    If you think this is a wrong alert, please let us know by replying to this email.
   {% endcall %}
 
   {% call text() %}

templates/emails/transactional/reply-must-use-personal-email.txt

@@ -8,8 +8,10 @@ Please note that sending from this alias only works from one of these mailboxes:
 - {{mailbox.email}}
 {% endfor %}
 
-
+This is to protect against "email spoofing", i.e. someone else sending emails from your mailbox.
 Indeed only you can send emails on behalf of your alias.
+If you think this is a wrong alert, please let us know by replying to this email.
+
 
 Best,
 SimpleLogin team.