Push and Email Notifications should follow "Teammate Name Display" setting (#4660)

* Push Notifications and Email Notifications should follow "Teammate Name Display" setting

* get the display name notification from the receiver

api/post.go

@@ -657,18 +657,26 @@ func sendNotifications(c *Context, post *model.Post, team *model.Team, channel *
 		updateMentionChans = append(updateMentionChans, Srv.Store.Channel().IncrementMentionCount(post.ChannelId, id))
 	}
 
-	senderName := ""
-
 	var sender *model.User
-	if post.IsSystemMessage() {
-		senderName = c.T("system.message.name")
-	} else if profile, ok := profileMap[post.UserId]; ok {
-		if value, ok := post.Props["override_username"]; ok && post.Props["from_webhook"] == "true" {
-			senderName = value.(string)
-		} else {
-			senderName = profile.Username
+	senderName := make(map[string]string)
+	for _, id := range mentionedUsersList {
+		senderName[id] = ""
+		if post.IsSystemMessage() {
+			senderName[id] = c.T("system.message.name")
+		} else if profile, ok := profileMap[post.UserId]; ok {
+			if value, ok := post.Props["override_username"]; ok && post.Props["from_webhook"] == "true" {
+				senderName[id] = value.(string)
+			} else {
+				//Get the Display name preference from the receiver
+				if result := <-Srv.Store.Preference().Get(id, model.PREFERENCE_CATEGORY_DISPLAY_SETTINGS, "name_format"); result.Err != nil {
+					// Show default sender's name if user doesn't set display settings.
+					senderName[id] = profile.Username
+				} else {
+					senderName[id] = profile.GetDisplayNameForPreference(result.Data.(model.Preference).Value)
+				}
+			}
+			sender = profile
 		}
-		sender = profile
 	}
 
 	if utils.Cfg.EmailSettings.SendEmailNotifications {
@@ -688,7 +696,7 @@ func sendNotifications(c *Context, post *model.Post, team *model.Team, channel *
 			}
 
 			if userAllowsEmails && status.Status != model.STATUS_ONLINE {
-				go sendNotificationEmail(c, post, profileMap[id], channel, team, senderName, sender)
+				go sendNotificationEmail(c, post, profileMap[id], channel, team, senderName[id], sender)
 			}
 		}
 	}
@@ -784,7 +792,7 @@ func sendNotifications(c *Context, post *model.Post, team *model.Team, channel *
 			}
 
 			if DoesStatusAllowPushNotification(profileMap[id], status, post.ChannelId) {
-				go sendPushNotification(post, profileMap[id], channel, senderName, true)
+				go sendPushNotification(post, profileMap[id], channel, senderName[id], true)
 			}
 		}
 
@@ -797,7 +805,7 @@ func sendNotifications(c *Context, post *model.Post, team *model.Team, channel *
 				}
 
 				if DoesStatusAllowPushNotification(profileMap[id], status, post.ChannelId) {
-					go sendPushNotification(post, profileMap[id], channel, senderName, false)
+					go sendPushNotification(post, profileMap[id], channel, senderName[id], false)
 				}
 			}
 		}
@@ -908,14 +916,6 @@ func sendNotificationEmail(c *Context, post *model.Post, user *model.User, chann
 		subjectText = userLocale("api.post.send_notifications_and_forget.message_subject")
 
 		senderDisplayName := senderName
-		if sender != nil {
-			if result := <-Srv.Store.Preference().Get(user.Id, model.PREFERENCE_CATEGORY_DISPLAY_SETTINGS, "name_format"); result.Err != nil {
-				// Show default sender's name if user doesn't set display settings.
-				senderDisplayName = senderName
-			} else {
-				senderDisplayName = sender.GetDisplayNameForPreference(result.Data.(model.Preference).Value)
-			}
-		}
 
 		mailTemplate = "api.templates.post_subject_in_direct_message"
 		mailParameters = map[string]interface{}{"SubjectText": subjectText, "TeamDisplayName": team.DisplayName,