diff --git a/src/api/mail_routes.py b/src/api/mail_routes.py
index fbd2318..d8922d5 100644
--- a/src/api/mail_routes.py
+++ b/src/api/mail_routes.py
@@ -56,7 +56,7 @@ def _task_to_mail(task: Task) -> Dict[str, Any]:
     return {
         "id": task.id,
         "title": task.title,
-        "from": meta.get("from", task.assigned_by),
+        "from": task.assigned_by or "unknown",
         "to": task.assignee,
         "status": task.status,
         "type": meta.get("type", "inform"),
@@ -80,15 +80,12 @@ async def list_mail(
 ):
     """Mail 列表（按时间倒序）"""
     bb = _bb()
-    tasks = bb.list_tasks(status=status, assignee=to_agent)
+    tasks = bb.list_tasks(status=status, assignee=to_agent, assigned_by=from_agent)
 
     mails = []
     for t in tasks:
         meta = _mail_meta(t)
-        # from 过滤
-        if from_agent and meta.get("from", t.assigned_by) != from_agent:
-            continue
-        # unread 过滤
+        # unread 过滤（must_haves JSON 内字段，无法 SQL WHERE）
         if unread is True and meta.get("is_read", False):
             continue
         mails.append(_task_to_mail(t))