diff --git a/email_handler.py b/email_handler.py
index 6ec45f46..970c6093 100644
--- a/email_handler.py
+++ b/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,
diff --git a/templates/emails/transactional/reply-must-use-personal-email.html b/templates/emails/transactional/reply-must-use-personal-email.html
index 7bd93185..7cb6a5c0 100644
--- a/templates/emails/transactional/reply-must-use-personal-email.html
+++ b/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.
+ 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.
{% endcall %}
{% call text() %}
diff --git a/templates/emails/transactional/reply-must-use-personal-email.txt b/templates/emails/transactional/reply-must-use-personal-email.txt
index 21e4b7fe..019a433e 100644
--- a/templates/emails/transactional/reply-must-use-personal-email.txt
+++ b/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.