diff --git a/src/aiomail/client.py b/src/aiomail/client.py
index c542ecd..c375266 100644
--- a/src/aiomail/client.py
+++ b/src/aiomail/client.py
@@ -229,10 +229,16 @@ class IMAPClient:
         return sorted(set(ids), reverse=True)
 
     async def fetch(self, email_id: int, *, icloud: bool = False) -> Optional[email.message.Message]:
-        """fetch and parse a full message by id"""
+        """fetch and parse a full message by id without setting \\Seen
+
+        uses BODY.PEEK[]: RFC822 / BODY[] on a SELECTed mailbox set \\Seen as a side effect
+        (RFC 3501), so a fetched-then-rejected message would vanish from every later UNSEEN
+        search. only mark_seen() flags a message. `icloud` is kept for compatibility and is
+        now a no-op (BODY.PEEK[] already works there)
+        """
         if not await self.ensure_connection():
             return None
-        part = "(BODY[])" if icloud else "(RFC822)"
+        part = "(BODY.PEEK[])"
         try:
             if self.use_uid:
                 result, data = await self._mail.uid("fetch", str(email_id), part)