diff --git a/devtools/deployments/opencloud_full/stalwart.yml b/devtools/deployments/opencloud_full/stalwart.yml
index dc1891bb83..92e796c404 100644
--- a/devtools/deployments/opencloud_full/stalwart.yml
+++ b/devtools/deployments/opencloud_full/stalwart.yml
@@ -7,7 +7,7 @@ services:
           - ${STALWART_DOMAIN:-stalwart.opencloud.test}
 
   stalwart:
-    image: ghcr.io/stalwartlabs/stalwart:v0.14.1-alpine
+    image: ghcr.io/stalwartlabs/stalwart:v0.15.0-alpine
     hostname: ${STALWART_DOMAIN:-stalwart.opencloud.test}
     networks:
       - opencloud-net
diff --git a/pkg/jmap/jmap_api_calendar.go b/pkg/jmap/jmap_api_calendar.go
index 1f32a23527..1e78dcb9a2 100644
--- a/pkg/jmap/jmap_api_calendar.go
+++ b/pkg/jmap/jmap_api_calendar.go
@@ -54,7 +54,7 @@ func (j *Client) QueryCalendarEvents(accountIds []string, session *Session, ctx
 	uniqueAccountIds := structs.Uniq(accountIds)
 
 	if sortBy == nil {
-		sortBy = []CalendarEventComparator{{Property: CalendarEventPropertyUpdated, IsAscending: false}}
+		sortBy = []CalendarEventComparator{{Property: CalendarEventPropertyStart, IsAscending: false}}
 	}
 
 	invocations := make([]Invocation, len(uniqueAccountIds)*2)
diff --git a/pkg/jmap/jmap_integration_event_test.go b/pkg/jmap/jmap_integration_event_test.go
index af014efa16..a4d1ee76b5 100644
--- a/pkg/jmap/jmap_integration_event_test.go
+++ b/pkg/jmap/jmap_integration_event_test.go
@@ -50,7 +50,7 @@ func TestEvents(t *testing.T) {
 		InCalendar: calendarId,
 	}
 	sortBy := []CalendarEventComparator{
-		{Property: CalendarEventPropertyCreated, IsAscending: true},
+		{Property: CalendarEventPropertyStart, IsAscending: true},
 	}
 
 	contactsByAccount, _, _, _, err := s.client.QueryCalendarEvents([]string{accountId}, session, t.Context(), s.logger, "", filter, sortBy, 0, 0)
diff --git a/pkg/jmap/jmap_integration_test.go b/pkg/jmap/jmap_integration_test.go
index 15691dc453..dbc8a17ea0 100644
--- a/pkg/jmap/jmap_integration_test.go
+++ b/pkg/jmap/jmap_integration_test.go
@@ -79,7 +79,7 @@ var (
 )
 
 const (
-	stalwartImage  = "ghcr.io/stalwartlabs/stalwart:v0.14.1-alpine"
+	stalwartImage  = "ghcr.io/stalwartlabs/stalwart:v0.15.0-alpine"
 	httpPort       = "8080"
 	imapsPort      = "993"
 	configTemplate = `
diff --git a/pkg/jscontact/jscontact_model.go b/pkg/jscontact/jscontact_model.go
index bbf5e52015..36cfbd8739 100644
--- a/pkg/jscontact/jscontact_model.go
+++ b/pkg/jscontact/jscontact_model.go
@@ -587,7 +587,7 @@ const (
 
 	// PhoneFeatures.
 
-	PhoneFeatureMobile     = PhoneFeature("cell") // TODO the spec says 'mobile', but Stalwart only supports 'cell'
+	PhoneFeatureMobile     = PhoneFeature("mobile")
 	PhoneFeatureVoice      = PhoneFeature("voice")
 	PhoneFeatureText       = PhoneFeature("text")
 	PhoneFeatureVideo      = PhoneFeature("video")