diff --git a/Sources/Actions/Notify.php b/Sources/Actions/Notify.php
index 47469a1385..841189290b 100644
--- a/Sources/Actions/Notify.php
+++ b/Sources/Actions/Notify.php
@@ -446,6 +446,20 @@ protected function setAlertPref(): void
 				$perfs = self::getNotifyPrefs((int) self::$member_info['id'], [$this->type . '_notify_' . $this->id], true);
 				$this->alert_pref = ((int) $perfs[(int) self::$member_info['id']][$this->type . '_notify_' . $this->id]) & self::PREF_ALERT;
 				break;
+
+			// And its mirror image: turn off the alerts and keep the emails.
+			case self::MODE_NO_ALERT:
+				$perfs = self::getNotifyPrefs((int) self::$member_info['id'], [$this->type . '_notify_' . $this->id], true);
+				$this->alert_pref = ((int) $perfs[(int) self::$member_info['id']][$this->type . '_notify_' . $this->id]) & self::PREF_EMAIL;
+				break;
+
+			// $this->mode comes straight from the query string, so it can be
+			// anything at all. Leaving it out here means the typed property
+			// below is never assigned, and reading it is a fatal error rather
+			// than a page.
+			default:
+				$this->alert_pref = self::PREF_NONE;
+				break;
 		}
 	}
 
diff --git a/Sources/Actions/NotifyBoard.php b/Sources/Actions/NotifyBoard.php
index 347129fa8b..bff78e1f84 100644
--- a/Sources/Actions/NotifyBoard.php
+++ b/Sources/Actions/NotifyBoard.php
@@ -61,7 +61,9 @@ protected function setId(): void
 	protected function saToMode(): void
 	{
 		if (!isset($_GET['mode']) && isset($_GET['sa'])) {
-			$_GET['mode'] = $_GET['sa'] == 'on' ? 3 : -1;
+			// 'off' is the unsubscribe link in the notification emails, so it
+			// means stop emailing me - not stop telling me anything at all.
+			$_GET['mode'] = $_GET['sa'] == 'on' ? parent::MODE_BOTH : parent::MODE_NO_EMAIL;
 			unset($_GET['sa']);
 		}
 	}
diff --git a/Sources/Actions/NotifyTopic.php b/Sources/Actions/NotifyTopic.php
index ff92980982..8c91df460d 100644
--- a/Sources/Actions/NotifyTopic.php
+++ b/Sources/Actions/NotifyTopic.php
@@ -62,7 +62,9 @@ protected function setId(): void
 	protected function saToMode(): void
 	{
 		if (!isset($_GET['mode']) && isset($_GET['sa'])) {
-			$_GET['mode'] = $_GET['sa'] == 'on' ? 3 : -1;
+			// 'off' is the unsubscribe link in the notification emails, so it
+			// means stop emailing me - not stop telling me anything at all.
+			$_GET['mode'] = $_GET['sa'] == 'on' ? parent::MODE_BOTH : parent::MODE_NO_EMAIL;
 			unset($_GET['sa']);
 		}
 	}
@@ -116,7 +118,7 @@ protected function changePref(): void
 			[
 				'id_member' => 'int', 'id_topic' => 'int', 'id_msg' => 'int', 'unwatched' => 'int',
 			],
-			$log,
+			[$log],
 			['id_member', 'id_topic'],
 		);