diff --git a/UI/PreferencesUI/English.lproj/Localizable.strings b/UI/PreferencesUI/English.lproj/Localizable.strings
index 47ab60c26..836df58d4 100644
--- a/UI/PreferencesUI/English.lproj/Localizable.strings
+++ b/UI/PreferencesUI/English.lproj/Localizable.strings
@@ -30,6 +30,8 @@
 "Disable auto reply on" = "Disable auto reply on";
 "Please specify your message and your email addresses for which you want to enable auto reply."
 = "Please specify your message and your email addresses for which you want to enable auto reply.";
+""Your vacation message must not end with a single dot on a line."
+= "Your vacation message must not end with a single dot on a line.";
 "End date of your auto reply must be in the future."
 = "End date of your auto reply must be in the future.";
 
diff --git a/UI/WebServerResources/UIxPreferences.js b/UI/WebServerResources/UIxPreferences.js
index b31a28d95..fc2627bb6 100644
--- a/UI/WebServerResources/UIxPreferences.js
+++ b/UI/WebServerResources/UIxPreferences.js
@@ -34,6 +34,10 @@ function savePreferences(sender) {
             showAlertDialog(_("Please specify your message and your email addresses for which you want to enable auto reply."));
             sendForm = false;
         }
+	if ($("autoReplyText").value.strip().endsWith('\n.')) {
+	  showAlertDialog(_("Your vacation message must not end with a single dot on a line."));
+	  sendForm = false;
+	}
         if ($("enableVacationEndDate") && $("enableVacationEndDate").checked) {
             var endDate = new Date($("vacationEndDate_date").value);
             var now = new Date();