IMAP: 线程中积压着草稿,因为每个客户端自动保存都会创建一行,而旧的草稿永远不会被删除

Reproduce:

1. Connect an IMAP mailbox whose client rewrites a draft on every save, meaning it appends a new message and expunges the old one. The trace below shows what that looks like.
2. Write a mail in the client and save it a few times, or let it autosave.
3. Let Twenty run its message import between the saves.
4. Open the thread in Twenty.