diff --git a/app/module/mail/ModuleMail.py b/app/module/mail/ModuleMail.py
index a5d9ee16..bba80776 100644
--- a/app/module/mail/ModuleMail.py
+++ b/app/module/mail/ModuleMail.py
@@ -1641,7 +1641,7 @@ def _action_move(self, client: ClientMailServer, folder_name: str, mail_uid: str
             raise RequestException("Missing or invalid destination folder for move action", err.ERROR_MISSING_ACTION_DATA)
 
         client.copy_mail_to_mailbox(folder_name, mail_uid, destination)
-        client.add_flags_to_mail(folder_name, mail_uid, ['\\Deleted'])
+        self._flag_deleted_and_expunge(client, folder_name, mail_uid)
 
         return {"action": "move", "mail_uid": mail_uid, "from_folder": folder_name, "to_folder": destination}
 
@@ -1658,7 +1658,7 @@ def _action_spam(self, client: ClientMailServer, folder_name: str, mail_uid: str
         """
         junk_folder = self.domain_mail_folder_name.get(cs.MAIL_FOLDER_JUNK, "Junk")
         client.copy_mail_to_mailbox(folder_name, mail_uid, junk_folder, create_dest=True)
-        client.add_flags_to_mail(folder_name, mail_uid, ['\\Deleted'])
+        self._flag_deleted_and_expunge(client, folder_name, mail_uid)
         return {"action": "spam", "mail_uid": mail_uid, "moved_to": junk_folder}
 
     def _action_ham(self, client: ClientMailServer, folder_name: str, mail_uid: str|list[str]) -> dict[str, Any]:
@@ -1675,7 +1675,7 @@ def _action_ham(self, client: ClientMailServer, folder_name: str, mail_uid: str|
         inbox_folder = self.domain_mail_folder_name.get(cs.MAIL_FOLDER_INBOX, "INBOX")
         junk_folder = self.domain_mail_folder_name.get(cs.MAIL_FOLDER_JUNK, "Junk")
         client.copy_mail_to_mailbox(junk_folder, mail_uid, inbox_folder)
-        client.add_flags_to_mail(folder_name, mail_uid, ['\\Deleted'])
+        self._flag_deleted_and_expunge(client, folder_name, mail_uid)
 
         return {"action": "ham", "mail_uid": mail_uid, "moved_to": inbox_folder}
 
@@ -1699,6 +1699,18 @@ def _action_copy(self, client: ClientMailServer, folder_name: str, mail_uid: str
 
         return {"action": "copy", "mail_uid": mail_uid, "from_folder": folder_name, "to_folder": destination}
 
+    def _flag_deleted_and_expunge(
+        self, client: ClientMailServer, folder_name: str, mail_uid: str|list[str]
+    ) -> None:
+        """Flag mails as deleted then expunge the source folder.
+
+        IMAP COPY + ``\\Deleted`` is not a move until EXPUNGE: without it the
+        original stays visible in the source folder (and a later move copies it
+        again, producing duplicates).
+        """
+        client.add_flags_to_mail(folder_name, mail_uid, ['\\Deleted'])
+        client.expunge_folder(folder_name, do_children=False)
+
     def _action_delete(self, client: ClientMailServer, folder_name: str, mail_uid: str|list[str], account_id: str) -> dict[str, Any]:
         """Delete a mail or a list of mails, honoring the user's ``SOGO_U_MAIL_DELETE_BEHAVIOR`` preference.
 
diff --git a/tests/test_module/test_mail/test_moduleMail.py b/tests/test_module/test_mail/test_moduleMail.py
index d7bbbcd5..caeccb13 100644
--- a/tests/test_module/test_mail/test_moduleMail.py
+++ b/tests/test_module/test_mail/test_moduleMail.py
@@ -44,6 +44,7 @@ def __init__(self):
         self.add_flags_calls = []
         self.remove_flags_calls = []
         self.delete_mails_by_uid_calls = []
+        self.expunge_folder_calls = []
         self.set_acl_calls = []
         self.delete_acl_calls = []
 
@@ -66,7 +67,8 @@ def delete_folder(self, folder_path, do_children=True):
         if self.delete_folder_result is not None:
             raise self.delete_folder_result
 
-    def expunge_folder(self, folder_path, do_subfolders=True):
+    def expunge_folder(self, folder_path, do_children=True):
+        self.expunge_folder_calls.append((folder_path, do_children))
         return self.expunge_folder_result
 
     def purge_folder(self, folder_path, before_date=None, do_children=False, permanently=False):
@@ -585,6 +587,7 @@ def test_perform_mail_action_move_success(monkeypatch):
     assert result["to_folder"] == "Archive"
     assert ("INBOX", "42", "Archive") in fake_client.copy_mail_to_mailbox_calls
     assert ("INBOX", "42", ['\\Deleted']) in fake_client.add_flags_calls
+    assert ("INBOX", False) in fake_client.expunge_folder_calls
 
 
 def test_perform_mail_action_move_missing_destination(monkeypatch):
@@ -610,6 +613,7 @@ def test_perform_mail_action_spam_success(monkeypatch):
     assert result["moved_to"] == "Junk"
     assert ("INBOX", "42", "Junk") in fake_client.copy_mail_to_mailbox_calls
     assert ("INBOX", "42", ['\\Deleted']) in fake_client.add_flags_calls
+    assert ("INBOX", False) in fake_client.expunge_folder_calls
 
 
 def test_perform_mail_action_ham_success(monkeypatch):
@@ -625,6 +629,7 @@ def test_perform_mail_action_ham_success(monkeypatch):
     assert result["moved_to"] == "INBOX"
     assert ("Junk", "42", "INBOX") in fake_client.copy_mail_to_mailbox_calls
     assert ("Junk", "42", ['\\Deleted']) in fake_client.add_flags_calls
+    assert ("Junk", False) in fake_client.expunge_folder_calls
 
 
 def test_perform_mail_action_copy_success(monkeypatch):
@@ -641,6 +646,7 @@ def test_perform_mail_action_copy_success(monkeypatch):
     assert ("INBOX", "42", "Archive") in fake_client.copy_mail_to_mailbox_calls
     # Copy should NOT delete the original mail
     assert ("INBOX", "42", ['\\Deleted']) not in fake_client.add_flags_calls
+    assert fake_client.expunge_folder_calls == []
 
 
 def test_perform_mail_action_copy_missing_destination(monkeypatch):
@@ -744,6 +750,7 @@ def test_perform_mail_batch_action_move_success(monkeypatch):
     assert result["to_folder"] == "Archive"
     assert ("INBOX", ["42", "43"], "Archive") in fake_client.copy_mail_to_mailbox_calls
     assert ("INBOX", ["42", "43"], ['\\Deleted']) in fake_client.add_flags_calls
+    assert ("INBOX", False) in fake_client.expunge_folder_calls
 
 
 def test_perform_mail_batch_action_move_missing_destination(monkeypatch):
@@ -769,6 +776,7 @@ def test_perform_mail_batch_action_spam_success(monkeypatch):
     assert result["moved_to"] == "Junk"
     assert ("INBOX", ["42", "43"], "Junk") in fake_client.copy_mail_to_mailbox_calls
     assert ("INBOX", ["42", "43"], ['\\Deleted']) in fake_client.add_flags_calls
+    assert ("INBOX", False) in fake_client.expunge_folder_calls
 
 
 def test_perform_mail_batch_action_ham_success(monkeypatch):
@@ -784,6 +792,7 @@ def test_perform_mail_batch_action_ham_success(monkeypatch):
     assert result["moved_to"] == "INBOX"
     assert ("Junk", ["42", "43"], "INBOX") in fake_client.copy_mail_to_mailbox_calls
     assert ("Junk", ["42", "43"], ['\\Deleted']) in fake_client.add_flags_calls
+    assert ("Junk", False) in fake_client.expunge_folder_calls
 
 
 def test_perform_mail_batch_action_copy_success(monkeypatch):
@@ -800,6 +809,7 @@ def test_perform_mail_batch_action_copy_success(monkeypatch):
     assert ("INBOX", ["42", "43"], "Archive") in fake_client.copy_mail_to_mailbox_calls
     # Copy should NOT delete the original mails
     assert ("INBOX", ["42", "43"], ['\\Deleted']) not in fake_client.add_flags_calls
+    assert fake_client.expunge_folder_calls == []
 
 
 def test_perform_mail_batch_action_copy_missing_destination(monkeypatch):