diff --git a/src/main/java/com/teaching/backend/common/ErrorCode.java b/src/main/java/com/teaching/backend/common/ErrorCode.java
index 4883d57..041682c 100644
--- a/src/main/java/com/teaching/backend/common/ErrorCode.java
+++ b/src/main/java/com/teaching/backend/common/ErrorCode.java
@@ -26,7 +26,8 @@ public enum ErrorCode {
     NO_AUTH_ERROR(40101, "无权限"),
     NOT_FOUND_ERROR(40400, "请求数据不存在"),
     CONTENT_EXISTS(41000, "内容存在"),
-
+    STUDENT_ROLE_CANT_MULTIPLESEND(41001, "学生用户不能群发，只能单发"),
+    LEAST_ONE_USER(41002, "最少选择一个用户"),
     KNOWS_EXISTS(41001, "存在关联的知识点"),
     ADD_RELATION_FAILED(41002, "添加关系失败"),
 
diff --git a/src/main/java/com/teaching/backend/service/impl/message/MessagesServiceImpl.java b/src/main/java/com/teaching/backend/service/impl/message/MessagesServiceImpl.java
index 6205d54..6b7b2c4 100644
--- a/src/main/java/com/teaching/backend/service/impl/message/MessagesServiceImpl.java
+++ b/src/main/java/com/teaching/backend/service/impl/message/MessagesServiceImpl.java
@@ -7,9 +7,11 @@ import com.teaching.backend.common.ErrorCode;
 import com.teaching.backend.exception.BusinessException;
 import com.teaching.backend.mapper.message.MessagesMapper;
 import com.teaching.backend.mapper.message.UserInboxMapper;
+import com.teaching.backend.mapper.umsAdmin.UmsUserMapper;
 import com.teaching.backend.model.dto.message.SysMessageDTO;
 import com.teaching.backend.model.entity.message.SysMessages;
 import com.teaching.backend.model.entity.message.UserInbox;
+import com.teaching.backend.model.entity.umsAdmin.UmsUser;
 import com.teaching.backend.service.message.IMessagesService;
 import lombok.extern.slf4j.Slf4j;
 import org.springframework.beans.BeanUtils;
@@ -38,6 +40,8 @@ public class MessagesServiceImpl extends ServiceImpl<MessagesMapper, SysMessages
 
     @Autowired
     private UserInboxMapper userInboxMapper;
+    @Autowired
+    private UmsUserMapper umsUserMapper;
     @Override
     @Transactional
     public String sendMessageToUserInbox(SysMessageDTO sysMessageDTO) {
@@ -51,8 +55,20 @@ public class MessagesServiceImpl extends ServiceImpl<MessagesMapper, SysMessages
         List<Long> receiverIds = Arrays.stream(sysMessageDTO.getReceiverId().split(","))
                 .map(Long::valueOf)
                 .collect(Collectors.toList());
+        if (receiverIds.size()<1){
+            throw new BusinessException(ErrorCode.LEAST_ONE_USER);
+        }
+
+        // 4.判断是什么用户，只有教师可以群发，学生只能单发
+        String roleId = umsUserMapper.selectOne(new LambdaQueryWrapper<>(UmsUser.class)
+                .eq(UmsUser::getId, sysMessageDTO.getSenderId())).getRoleId();
+        if(roleId.equals("2")){
+            if (receiverIds.size()>1){
+                throw new BusinessException(ErrorCode.STUDENT_ROLE_CANT_MULTIPLESEND);
+            }
+        }
 
-        // 4.数据写入收件箱
+        // 5.数据写入收件箱
         List<UserInbox> userInboxes = receiverIds.stream()
                 .map(receiverId -> {
                     UserInbox userInbox = new UserInbox();
@@ -68,7 +84,7 @@ public class MessagesServiceImpl extends ServiceImpl<MessagesMapper, SysMessages
             throw new BusinessException(ErrorCode.OPERATION_ERROR, "收件箱数据插入失败！");
         }
 
-        // 5.更新或保存消息数据
+        // 6.更新或保存消息数据
         SysMessages sysMessages = new SysMessages();
         BeanUtils.copyProperties(sysMessageDTO, sysMessages);
         sysMessages.setId(messageId);
diff --git a/src/main/java/com/teaching/backend/service/impl/message/UserInboxServiceImpl.java b/src/main/java/com/teaching/backend/service/impl/message/UserInboxServiceImpl.java
index 654eb61..5c41903 100644
--- a/src/main/java/com/teaching/backend/service/impl/message/UserInboxServiceImpl.java
+++ b/src/main/java/com/teaching/backend/service/impl/message/UserInboxServiceImpl.java
@@ -125,10 +125,10 @@ public class UserInboxServiceImpl extends ServiceImpl<UserInboxMapper, UserInbox
 
     @Override
     public PageDTO<SysMessageVO> querySendMessages(MessagesQuery messagesQuery) {
-        // 初始化一个按发送时间降序排序的Page对象
+        // 1. 初始化一个按发送时间降序排序的Page对象
         Page<SysMessages> page = messagesQuery.toMpPage("send_time", false);
 
-        // 根据条件查询SysMessages表
+        // 2. 根据条件查询SysMessages表
         Page<SysMessages> p = messagesService.page(page,
                 new LambdaQueryWrapper<SysMessages>()
                         .eq(SysMessages::getSenderId, messagesQuery.getUserId())
@@ -137,7 +137,7 @@ public class UserInboxServiceImpl extends ServiceImpl<UserInboxMapper, UserInbox
                         .select(SysMessages::getId, SysMessages::getCourseId, SysMessages::getTitle, SysMessages::getSendTime)
         );
 
-        // 将Page<SysMessages>转换为PageDTO<SysMessageVO>
+        // 3. 将Page<SysMessages>转换为PageDTO<SysMessageVO>
         PageDTO<SysMessageVO> messages = PageDTO.of(p, SysMessageVO.class);
         List<SysMessageVO> messagesList = messages.getList();
 
@@ -145,31 +145,33 @@ public class UserInboxServiceImpl extends ServiceImpl<UserInboxMapper, UserInbox
             throw new BusinessException(ErrorCode.MESSAGE_NO_EXIT);
         }
 
-        // 批量查询课程名称
+        // 4. 批量查询课程ID
         Set<String> courseIds = messagesList.stream()
                 .map(SysMessageVO::getCourseId)
                 .filter(Objects::nonNull)
                 .collect(Collectors.toSet());
 
+        // 5. 批量查询课程ID对应的课程名称 并把ID:name 对应到一起
         Map<String, String> courseNames = coursesMapper.selectBatchIds(courseIds).stream()
                 .collect(Collectors.toMap(Courses::getId, Courses::getName));
 
-        // 批量查询所有用户收件箱数据
+        // 6. 批量查询当前用户对应的消息集合messageIds
         Set<Long> messageIds = messagesList.stream()
                 .map(SysMessageVO::getId)
                 .collect(Collectors.toSet());
 
+        // 在用户邮箱中批量查询 对应消息的 信息（消息id，接受者id，是否已读）
         List<UserInbox> allUserInboxes = userInboxMapper.selectList(
                 new LambdaQueryWrapper<UserInbox>()
                         .in(UserInbox::getMessageId, messageIds)
                         .select(UserInbox::getMessageId, UserInbox::getReceiverId, UserInbox::getIsRead)
         );
 
-        // 将UserInbox数据按消息ID进行分组
+        // 7. 将UserInbox数据按消息ID进行分组（已经初步得到了消息的详情）
         Map<Long, List<UserInbox>> userInboxesByMessageId = allUserInboxes.stream()
                 .collect(Collectors.groupingBy(UserInbox::getMessageId));
 
-        // 缓存用户名称以避免重复查询
+        // 8. 缓存用户名称以避免重复查询
         Map<Long, String> userNamesCache = new HashMap<>();
 
         for (SysMessageVO sysMessageVO : messagesList) {
@@ -200,7 +202,7 @@ public class UserInboxServiceImpl extends ServiceImpl<UserInboxMapper, UserInbox
                                     UmsTeacher umsTeacher = umsTeacherMapper.selectOne(
                                             new LambdaQueryWrapper<UmsTeacher>().eq(UmsTeacher::getUserId, id)
                                     );
-                                    return umsTeacher != null ? umsTeacher.getName() : null;
+                                    return umsTeacher != null ? umsTeacher.getName() : "教师不存在";
                                 }
                             });
 
@@ -212,20 +214,27 @@ public class UserInboxServiceImpl extends ServiceImpl<UserInboxMapper, UserInbox
             }
         }
 
-        // 更新PageDTO中的消息列表并返回
+        // 9. 更新PageDTO中的消息列表并返回
         messages.setList(messagesList);
         return messages;
     }
 
 
+
     @Override
     public SysMessageVO getMessageDetail(MessagesQuery messagesQuery) {
+        Long count = userInboxMapper.selectCount(new LambdaQueryWrapper<>(UserInbox.class)
+                .eq(UserInbox::getMessageId, messagesQuery.getMessageId())
+                .eq(UserInbox::getReceiverId, messagesQuery.getUserId()));
+        if (!(count > 0)){
+            throw new BusinessException(ErrorCode.MESSAGE_NO_EXIT);
+        }
         SysMessages sysMessage = messagesService.getById(messagesQuery.getMessageId());
         SysMessageVO sysMessageVO = new SysMessageVO();
         sysMessageVO.setId(messagesQuery.getMessageId());
         sysMessageVO.setContent(sysMessage.getContent());
         sysMessageVO.setSenderId(messagesQuery.getUserId());
-//         获取发件人信息
+        //获取发件人信息
         UmsTeacher umsTeacher = umsTeacherMapper.selectOne(
                 new LambdaQueryWrapper<UmsTeacher>()
                         .eq(UmsTeacher::getUserId, sysMessage.getSenderId()));