1470724 - Move that fails halfway leaves duplicate messages

Status: UNCONFIRMED

(MailNews Core :: Networking: IMAP, defect)

Description

[kjell]

User Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:60.0) Gecko/20100101 Firefox/60.0
Build ID: 20180605171542

Steps to reproduce:

Trying to move messages to a Gmap inbox via IMAP.

1. Select a number of messages. Make sure somewhere in the middle there's a message that's 10+ Mbyte in size (which will cause the operation to time out as reported in bug 1470720).
2. Drag the messages and drop them on the Gmail IMAP account's inbox folder.
3. Wait for the timeout to happen.
4. Check which messages are present in the source folder and which messages are present in the target folder.


Actual results:

The target folder will contain all messages before the large one (that caused the timeout), but all of them are still present in the source folder. This means that the messages before the failing on are now duplicated.


Expected results:

The messages that were successfully moved to the target folder should have been removed from the source folder. As a less helpful alternative, a full "rollback" should be performed, i.e. the messages that were successfully moved should be removed from the target folder.

This is a major problem when moving many messages to an IMAP folder, because if you try to move all messages in a folder with thousands of messages, and it fails somewhere, you end up with thousands of duplicates. You can manually check which ones got copied and manually remove them from the source, and then repeat. But it's a lot of work comparing folder contents.