diff --git a/bin/recategorize-messages.py b/bin/recategorize-messages.py
index 911c13062..6e7f9aa2f 100755
--- a/bin/recategorize-messages.py
+++ b/bin/recategorize-messages.py
@@ -1,6 +1,7 @@
 #!/usr/bin/env python
 
 import datetime
+from collections.abc import Iterable
 
 import click
 from sqlalchemy.orm import Query
@@ -13,64 +14,84 @@
 from inbox.models.session import global_session_scope, session_scope
 
 
-def fetch_message_ids(
+def yield_account_id_and_message_ids(
     *,
-    account_id: int | None,
+    only_account_id: int | None,
     date_start: datetime.date | None,
     date_end: datetime.date | None,
     only_inbox: bool,
-) -> list[int]:
-    query = Query([Message.id])
-    if account_id:
-        query = query.filter(Message.namespace.has(Namespace.account_id == account_id))
-    if only_inbox:
-        inbox_folder = ImapUid.folder.has(Folder._canonical_name == "INBOX")
-        query = query.filter(Message.imapuids.any(inbox_folder))
-    if date_start:
-        query = query.filter(Message.created_at >= date_start)
-    if date_end:
-        query = query.filter(Message.created_at < date_end)
+) -> Iterable[int, list[int]]:
+    namespace_query = Query([Namespace.account_id, Namespace.id])
+    if only_account_id:
+        namespace_query = namespace_query.filter(
+            Namespace.account_id == only_account_id
+        )
 
     with global_session_scope() as session:
-        message_ids = [message_id for message_id, in query.with_session(session)]
+        account_id_to_namespace_id = {
+            account_id: namespace_id
+            for account_id, namespace_id in namespace_query.with_session(session)
+        }
 
-    return message_ids
+    for account_id, namespace_id in account_id_to_namespace_id.items():
+        query = Query([Message.id]).filter(Message.namespace_id == namespace_id)
+
+        if only_inbox:
+            inbox_folder = ImapUid.folder.has(Folder._canonical_name == "INBOX")
+            query = query.filter(Message.imapuids.any(inbox_folder))
+        if date_start:
+            query = query.filter(Message.created_at >= date_start)
+        if date_end:
+            query = query.filter(Message.created_at < date_end)
+
+        with global_session_scope() as session:
+            message_ids = [message_id for message_id, in query.with_session(session)]
+
+        yield account_id, message_ids
 
 
 @click.command()
 @click.option("--date-start", type=click.DateTime(formats=["%Y-%m-%d"]), default=None)
 @click.option("--date-end", type=click.DateTime(formats=["%Y-%m-%d"]), default=None)
-@click.option("--account-id", type=int, default=None)
+@click.option("--only-account-id", type=int, default=None)
 @click.option("--only-inbox", is_flag=True, default=False)
+@click.option("--dry-run/--no-dry-run", default=True)
 def main(
-    account_id: int | None,
+    only_account_id: int | None,
     only_inbox: bool,
     date_start: datetime.date | None,
     date_end: datetime.date | None,
+    dry_run: bool,
 ) -> None:
-    message_ids = fetch_message_ids(
-        account_id=account_id,
+    print(
+        f"Settings: {only_account_id=},{only_inbox=},{date_start=},{date_end=},{dry_run=}"
+    )
+
+    def session_factory():
+        return global_session_scope() if dry_run else session_scope(None)
+
+    for account_id, message_ids in yield_account_id_and_message_ids(
+        only_account_id=only_account_id,
         date_start=date_start,
         date_end=date_end,
         only_inbox=only_inbox,
-    )
+    ):
+        print(f"{account_id=},{len(message_ids)=}")
 
-    print(f"Found {len(message_ids)}")
-
-    for message_id in message_ids:
-        with session_scope(None) as session:
-            message = session.query(Message).get(message_id)
-            old_categories = set(
-                category.display_name for category in message.categories
-            )
-            update_message_metadata(session, message.account, message, message.is_draft)
-            new_categories = set(
-                category.display_name for category in message.categories
-            )
-            if old_categories != new_categories:
-                print(
-                    f"Message {message_id} categories changed from {old_categories} to {new_categories}"
+        for message_id in message_ids:
+            with session_factory() as session:
+                message = session.query(Message).get(message_id)
+                old_categories = set(
+                    category.display_name for category in message.categories
+                )
+                update_message_metadata(
+                    session, message.account, message, message.is_draft
+                )
+                new_categories = set(
+                    category.display_name for category in message.categories
                 )
+                if old_categories != new_categories:
+                    print(f"\t{message_id=},{old_categories=} to {new_categories}=")
 
 
 if __name__ == "__main__":