diff --git a/connector/mattermost/mattermost.go b/connector/mattermost/mattermost.go
index 41f956b..7c776d8 100644
--- a/connector/mattermost/mattermost.go
+++ b/connector/mattermost/mattermost.go
@@ -27,7 +27,9 @@ type Mattermost struct {
 	conn *matterclient.MMClient
 	handlerStopChan chan bool
 
-	usermap map[string]string		// map username to user id
+	usermap map[string]string		// map username to mm user id
+	sentjoinedmap map[string]bool	// map username/room name to bool
+	userdisplaynamemap map[UserID]string	 // map username to last displayname
 }
 
 
@@ -264,6 +266,8 @@ func (mm *Mattermost) Close() {
 func (mm *Mattermost) handleConnected() {
 	mm.handlerStopChan = make(chan bool)
 	mm.usermap = make(map[string]string)
+	mm.sentjoinedmap = make(map[string]bool)
+	mm.userdisplaynamemap = make(map[UserID]string)
 	go mm.handleLoop(mm.conn.MessageChan, mm.handlerStopChan)
 
 	fmt.Printf("Connected to mattermost\n")
@@ -323,6 +327,14 @@ func (mm *Mattermost) handlePosted(msg *model.WebSocketEvent) error {
 	}
 	userId := UserID(fmt.Sprintf("%s@%s", user.Username, mm.server))
 
+	if lastdn, ok := mm.userdisplaynamemap[userId]; !ok || lastdn != user.Nickname {
+		log.Warnf("Update displayname %s %s", userId, user.Nickname)
+		mm.handler.UserInfoUpdated(userId, &UserInfo{
+			DisplayName: user.Nickname,
+		})
+		mm.userdisplaynamemap[userId] = user.Nickname
+	}
+
 	// Build message event
 	msg_ev := &Event{
 		Author: userId,
@@ -348,12 +360,15 @@ func (mm *Mattermost) handlePosted(msg *model.WebSocketEvent) error {
 			return fmt.Errorf("Invalid channel id")
 		}
 
-		// TODO don't join everytime
-		mm.handler.Event(&Event{
-			Author: userId,
-			Room: roomId,
-			Type: EVENT_JOIN,
-		})
+		cache_key := fmt.Sprintf("%s / %s", userId, roomId)
+		if _, ok := mm.sentjoinedmap[cache_key]; !ok {
+			mm.handler.Event(&Event{
+				Author: userId,
+				Room: roomId,
+				Type: EVENT_JOIN,
+			})
+			mm.sentjoinedmap[cache_key] = true
+		}
 
 		if post.Type == "system_header_change" {
 			new_header := post.Props["new_header"].(string)