diff --git a/docs/changelog.md b/docs/changelog.md
index a9c83a5..871cfbb 100644
--- a/docs/changelog.md
+++ b/docs/changelog.md
@@ -2,6 +2,7 @@
 
 ## [v0.3.5](https://github.com/0x2142/frigate-notify/releases/tag/v0.3.5) - Upcoming Release
  - Fixed issue where built-in alert templates were not being included in binary releases
+ - Fixed issue where a notification may not be sent if previous event update from Frigate did not contain a snapshot
  - Added `from` & `ignoressl` config items to `smtp` notifier
 
 ## [v0.3.4](https://github.com/0x2142/frigate-notify/releases/tag/v0.3.4) - Aug 15 2024
diff --git a/events/cache.go b/events/cache.go
new file mode 100644
index 0000000..776ae10
--- /dev/null
+++ b/events/cache.go
@@ -0,0 +1,88 @@
+package frigate
+
+import (
+	"slices"
+	"strings"
+	"time"
+
+	"github.com/0x2142/frigate-notify/models"
+	"github.com/rs/zerolog/log"
+
+	"github.com/maypok86/otter"
+)
+
+var zoneCache otter.Cache[string, []string]
+
+func InitZoneCache() {
+	var err error
+	log.Debug().Msg("Setting up zone cache...")
+	zoneCache, err = otter.MustBuilder[string, []string](500).WithTTL(1 * time.Hour).Build()
+	if err != nil {
+		log.Warn().
+			Err(err).
+			Msg("Error setting up zone cache")
+	}
+	log.Debug().Msg("Zone cache ready")
+}
+
+func CloseZoneCache() {
+	log.Debug().Msg("Cache tear down")
+	zoneCache.Close()
+}
+
+// Add zone to list of zones that have already generated notifications for specified event ID
+func setZoneAlerted(event models.Event) {
+	// Get current list of zones by event ID, if it exists
+	alreadyAlerted, _ := zoneCache.Get(event.ID)
+	alreadyAlerted = append(alreadyAlerted, event.CurrentZones...)
+	// Remove duplicates
+	slices.Sort(alreadyAlerted)
+	alreadyAlerted = slices.Compact(alreadyAlerted)
+	// Update cache with new list
+	zoneCache.Set(event.ID, alreadyAlerted)
+}
+
+// Query cache to see if zone already generated alert
+func zoneAlreadyAlerted(event models.Event) bool {
+	// Check if event already in cache & if so, get contents
+	alreadyAlerted, ok := zoneCache.Get(event.ID)
+	// If event not found, create cache entry & add zones
+	if !ok {
+		log.Debug().
+			Str("event_id", event.ID).
+			Str("camera", event.Camera).
+			Str("zones", strings.Join(event.CurrentZones, ",")).
+			Msg("Event not in cache, adding...")
+		setZoneAlerted(event)
+		return false
+	}
+	// If event found, check to see if there are any new zones to notify on
+	for _, zone := range event.CurrentZones {
+		if !slices.Contains(alreadyAlerted, zone) {
+			log.Debug().
+				Str("event_id", event.ID).
+				Str("camera", event.Camera).
+				Str("zones", strings.Join(event.CurrentZones, ",")).
+				Msg("Found new zone not in cache")
+			setZoneAlerted(event)
+			return false
+		}
+	}
+	// If no new zones, then assume all have been notified already
+	log.Debug().
+		Str("event_id", event.ID).
+		Str("camera", event.Camera).
+		Str("zones", strings.Join(event.CurrentZones, ",")).
+		Msg("All zones in event have already notified")
+	return true
+}
+
+// Remove zone alert cache for event ID
+func delZoneAlerted(event models.Event) {
+	zoneCache.Delete(event.ID)
+	log.Debug().
+		Str("event_id", event.ID).
+		Str("camera", event.Camera).
+		Str("zones", strings.Join(event.CurrentZones, ",")).
+		Msg("Event removed from cache")
+}
diff --git a/events/cache_test.go b/events/cache_test.go
new file mode 100644
index 0000000..1825db0
--- /dev/null
+++ b/events/cache_test.go
@@ -0,0 +1,75 @@
+package frigate
+
+import (
+	"testing"
+
+	"github.com/0x2142/frigate-notify/models"
+)
+
+func TestSetZoneAlerted(t *testing.T) {
+	// Setup
+	InitZoneCache()
+	defer CloseZoneCache()
+	event := models.Event{ID: "test-event-id", CurrentZones: []string{"test_zone", "test_zone"}}
+
+	setZoneAlerted(event)
+
+	expected := []string{"test_zone"}
+	result, ok := zoneCache.Get(event.ID)
+	if !ok {
+		t.Error("Could not find event ID")
+	}
+
+	// Check if zone added
+	if result[0] != expected[0] {
+		t.Errorf("Expected: %s, Got: %s", expected, result)
+	}
+
+	// Check if duplicates removed
+	if len(result) != 1 {
+		t.Errorf("Expected: %s, Got: %s", expected, result)
+	}
+}
+
+func TestZoneAlreadyAlerted(t *testing.T) {
+	// Setup
+	InitZoneCache()
+	defer CloseZoneCache()
+	event := models.Event{ID: "test-event-id", CurrentZones: []string{"test_zone", "test_zone"}}
+
+	// Test new event
+	result := zoneAlreadyAlerted(event)
+	if result != false {
+		t.Errorf("Expected: false, Got: %v", result)
+	}
+
+	// Test adding new zone to existing event
+	event.CurrentZones = append(event.CurrentZones, "another_zone")
+	result = zoneAlreadyAlerted(event)
+	if result != false {
+		t.Errorf("Expected: false, Got: %v", result)
+	}
+
+	// Test event that has already generated alert
+	result = zoneAlreadyAlerted(event)
+	if result != true {
+		t.Errorf("Expected: true, Got: %v", result)
+	}
+}
+
+func TestDelZoneAlerted(t *testing.T) {
+	// Setup
+	InitZoneCache()
+	defer CloseZoneCache()
+	event := models.Event{ID: "test-event-id", CurrentZones: []string{"test_zone", "test_zone"}}
+
+	// Create new cache entry
+	setZoneAlerted(event)
+
+	// Test delete
+	delZoneAlerted(event)
+	_, ok := zoneCache.Get(event.ID)
+	if ok {
+		t.Errorf("Cache entry not deleted")
+	}
+}
diff --git a/events/filters.go b/events/filters.go
index 5f91b6e..93d17ff 100644
--- a/events/filters.go
+++ b/events/filters.go
@@ -13,6 +13,22 @@ import (
 
 // checkEventFilters processes incoming event through configured filters to determine if it should generate a notification
 func checkEventFilters(event models.Event) bool {
+	// Drop event if no snapshot or clip is available - Event is likely being filtered on Frigate side.
+	// For example, if a camera has `required_zones` set - then there may not be any clip or snap until
+	// object moves into required zone
+	if !event.HasClip && !event.HasSnapshot {
+		log.Info().
+			Str("event_id", event.ID).
+			Msg("Event dropped - No snapshot or clip available")
+		return false
+	}
+	// Drop event if no snapshot & skip_nosnap is true
+	if !event.HasSnapshot && strings.ToLower(config.ConfigData.Alerts.General.NoSnap) == "drop" {
+		log.Info().
+			Str("event_id", event.ID).
+			Msg("Event dropped - No snapshot available")
+		return false
+	}
 	// Check quiet hours
 	if isQuietHours() {
 		log.Info().
diff --git a/events/mqtt.go b/events/mqtt.go
index 8e1c10b..a4fc181 100644
--- a/events/mqtt.go
+++ b/events/mqtt.go
@@ -92,21 +92,8 @@ func processEvent(client mqtt.Client, msg mqtt.Message) {
 			return
 		}
 
-		// Skip update events where zone didn't change
-		// Compares current detected zone to previous list of zones entered
-		zoneChanged := false
-		for _, zone := range event.After.CurrentZones {
-			if !slices.Contains(event.Before.EnteredZones, zone) {
-				zoneChanged = true
-				log.Debug().
-					Str("event_id", event.After.ID).
-					Str("camera", event.After.Camera).
-					Str("label", event.After.Label).
-					Str("zones", strings.Join(event.After.CurrentZones, ",")).
-					Msg("Object entered new zone")
-			}
-		}
-		if event.Type == "update" && !zoneChanged {
+		// Check if already notified on zones
+		if zoneAlreadyAlerted(event.After.Event) {
 			log.Info().
 				Str("event_id", event.After.ID).
 				Str("camera", event.After.Camera).
@@ -114,6 +101,13 @@ func processEvent(client mqtt.Client, msg mqtt.Message) {
 				Str("zones", strings.Join(event.After.CurrentZones, ",")).
 				Msg("Event dropped - Already notified on this zone")
 			return
+		} else {
+			log.Debug().
+				Str("event_id", event.After.ID).
+				Str("camera", event.After.Camera).
+				Str("label", event.After.Label).
+				Str("zones", strings.Join(event.After.CurrentZones, ",")).
+				Msg("Object entered new zone")
 		}
 
 		// If snapshot was collected, pull down image to send with alert
@@ -127,6 +121,15 @@ func processEvent(client mqtt.Client, msg mqtt.Message) {
 		// Send alert with snapshot
 		notifier.SendAlert(event.After.Event, snapshotURL, snapshot, event.After.ID)
 	}
+
+	// Clear event cache entry when event ends
+	if event.Type == "end" {
+		log.Debug().
+			Str("event_id", event.After.ID).
+			Msg("Event ended")
+		delZoneAlerted(event.After.Event)
+		return
+	}
 }
 
 // connectionLostHandler logs error message on MQTT connection loss
diff --git a/go.mod b/go.mod
index dab3468..af7cff9 100644
--- a/go.mod
+++ b/go.mod
@@ -17,10 +17,13 @@ require (
 require (
 	github.com/disgoorg/json v1.1.0 // indirect
 	github.com/disgoorg/snowflake/v2 v2.0.1 // indirect
+	github.com/dolthub/maphash v0.1.0 // indirect
+	github.com/gammazero/deque v0.2.1 // indirect
 	github.com/gorilla/websocket v1.5.1 // indirect
 	github.com/kr/pretty v0.3.1 // indirect
 	github.com/mattn/go-colorable v0.1.13 // indirect
 	github.com/mattn/go-isatty v0.0.20 // indirect
+	github.com/maypok86/otter v1.2.2 // indirect
 	github.com/mitchellh/mapstructure v1.5.0 // indirect
 	github.com/pelletier/go-toml/v2 v2.1.1 // indirect
 	github.com/rogpeppe/go-internal v1.12.0 // indirect
diff --git a/go.sum b/go.sum
index 1eb9052..68be7cc 100644
--- a/go.sum
+++ b/go.sum
@@ -9,8 +9,12 @@ github.com/disgoorg/json v1.1.0 h1:7xigHvomlVA9PQw9bMGO02PHGJJPqvX5AnwlYg/Tnys=
 github.com/disgoorg/json v1.1.0/go.mod h1:BHDwdde0rpQFDVsRLKhma6Y7fTbQKub/zdGO5O9NqqA=
 github.com/disgoorg/snowflake/v2 v2.0.1 h1:CuUxGLwggUxEswZOmZ+mZ5i0xSumQdXW9tXW7uGqe+0=
 github.com/disgoorg/snowflake/v2 v2.0.1/go.mod h1:SPU9c2CNn5DSyb86QcKtdZgix9osEtKrHLW4rMhfLCs=
+github.com/dolthub/maphash v0.1.0 h1:bsQ7JsF4FkkWyrP3oCnFJgrCUAFbFf3kOl4L/QxPDyQ=
+github.com/dolthub/maphash v0.1.0/go.mod h1:gkg4Ch4CdCDu5h6PMriVLawB7koZ+5ijb9puGMV50a4=
 github.com/eclipse/paho.mqtt.golang v1.4.3 h1:2kwcUGn8seMUfWndX0hGbvH8r7crgcJguQNCyp70xik=
 github.com/eclipse/paho.mqtt.golang v1.4.3/go.mod h1:CSYvoAlsMkhYOXh/oKyxa8EcBci6dVkLCbo5tTC1RIE=
+github.com/gammazero/deque v0.2.1 h1:qSdsbG6pgp6nL7A0+K/B7s12mcCY/5l5SIUpMOl+dC0=
+github.com/gammazero/deque v0.2.1/go.mod h1:LFroj8x4cMYCukHJDbxFCkT+r9AndaJnFMuZDV34tuU=
 github.com/go-telegram-bot-api/telegram-bot-api/v5 v5.5.1 h1:wG8n/XJQ07TmjbITcGiUaOtXxdrINDz1b0J1w0SzqDc=
 github.com/go-telegram-bot-api/telegram-bot-api/v5 v5.5.1/go.mod h1:A2S0CWkNylc2phvKXWBBdD3K0iGnDBGbzRpISP2zBl8=
 github.com/godbus/dbus/v5 v5.0.4/go.mod h1:xhWf0FNVPg57R7Z0UbKHbJfkEywrmjJnf7w5xrFpKfA=
@@ -33,6 +37,8 @@ github.com/mattn/go-isatty v0.0.16/go.mod h1:kYGgaQfpe5nmfYZH+SKPsOc2e4SrIfOl2e/
 github.com/mattn/go-isatty v0.0.19/go.mod h1:W+V8PltTTMOvKvAeJH7IuucS94S2C6jfK/D7dTCTo3Y=
 github.com/mattn/go-isatty v0.0.20 h1:xfD0iDuEKnDkl03q4limB+vH+GxLEtL/jb4xVJSWWEY=
 github.com/mattn/go-isatty v0.0.20/go.mod h1:W+V8PltTTMOvKvAeJH7IuucS94S2C6jfK/D7dTCTo3Y=
+github.com/maypok86/otter v1.2.2 h1:jJi0y8ruR/ZcKmJ4FbQj3QQTqKwV+LNrSOo2S1zbF5M=
+github.com/maypok86/otter v1.2.2/go.mod h1:mKLfoI7v1HOmQMwFgX4QkRk23mX6ge3RDvjdHOWG4R4=
 github.com/mitchellh/mapstructure v1.5.0 h1:jeMsZIYE/09sWLaz43PL7Gy6RuMjD2eJVyuac5Z2hdY=
 github.com/mitchellh/mapstructure v1.5.0/go.mod h1:bFUtVrKA4DC2yAKiSyO/QUcy7e+RRV2QTWOzhPopBRo=
 github.com/pelletier/go-toml/v2 v2.1.1 h1:LWAJwfNvjQZCFIDKWYQaM62NcYeYViCmWIwmOStowAI=
diff --git a/main.go b/main.go
index fc2228c..a4e38dd 100644
--- a/main.go
+++ b/main.go
@@ -17,7 +17,7 @@ import (
 	"github.com/0x2142/frigate-notify/util"
 )
 
-var APP_VER = "v0.3.4"
+var APP_VER = "v0.3.5-dev"
 var debug, debugenv bool
 var jsonlog, jsonlogenv bool
 var nocolor, nocolorenv bool
@@ -88,6 +88,10 @@ func main() {
 	}
 	// Connect MQTT
 	if config.ConfigData.Frigate.MQTT.Enabled {
+		// Set up event cache
+		frigate.InitZoneCache()
+		defer frigate.CloseZoneCache()
+
 		log.Debug().Msg("Connecting to MQTT Server...")
 		frigate.SubscribeMQTT()
 		log.Info().Msg("App running. Press Ctrl-C to quit.")
diff --git a/notifier/alerts.go b/notifier/alerts.go
index 4629fbc..c640462 100644
--- a/notifier/alerts.go
+++ b/notifier/alerts.go
@@ -22,22 +22,6 @@ var TemplateFiles embed.FS
 func SendAlert(event models.Event, snapshotURL string, snapshot io.Reader, eventid string) {
 	// Add Frigate Major version metadata
 	event.Extra.FrigateMajorVersion = config.ConfigData.Frigate.Version
-	// Drop event if no snapshot or clip is available - Event is likely being filtered on Frigate side.
-	// For example, if a camera has `required_zones` set - then there may not be any clip or snap until
-	// object moves into required zone
-	if !event.HasClip && !event.HasSnapshot {
-		log.Info().
-			Str("event_id", event.ID).
-			Msg("Event dropped - No snapshot or clip available")
-		return
-	}
-	// Drop event if no snapshot & skip_nosnap is true
-	if !event.HasSnapshot && strings.ToLower(config.ConfigData.Alerts.General.NoSnap) == "drop" {
-		log.Info().
-			Str("event_id", event.ID).
-			Msg("Event dropped - No snapshot available")
-		return
-	}
 	// Create copy of snapshot for each alerting method
 	var snap []byte
 	if snapshot != nil {