优化完善，BUG修复

mailbox-lan/src/main/java/com/biutag/lan/flow/node/FirstSignFlow.java

@@ -23,7 +23,6 @@ import org.springframework.transaction.annotation.Transactional;
 import org.springframework.util.Assert;
 
 import java.time.LocalDateTime;
-import java.util.Objects;
 
 /**
  * 市局专班签收
@@ -55,7 +54,10 @@ public class FirstSignFlow extends Flow {
             // 无效类、终止类
             if (mailFirstCategory.equals(MailCategoryEnums.INVALID.getName()) ||
                     mailFirstCategory.equals(MailCategoryEnums.TERMINATION.getName())) {
-                return signFlow.invalidMailFlow(mailId, data);
+                Flow flow = signFlow.invalidMailFlow(mailId, data);
+                mailService.update(new LambdaUpdateWrapper<Mail>().eq(Mail::getId, mailId)
+                        .set(Mail::getFirstDeptId, AdminThreadLocal.getDeptId()));
+                return flow;
             }
             LambdaUpdateWrapper<Mail> updateWrapper = new LambdaUpdateWrapper<>();
             // 咨询求助、工作建议