Move operations on a multi-mail selection across shared mailboxes lead to only a part of the selection being moved.

[ganthern]

Bug in web app

Describe the bug
When you search for mail in all folders, it's possible for mail in any mailbox to turn up in the result and be selected together.
Moving such a cross-mailbox selection to any folder will cause only part of the mail to be moved (without an indication that the operation was only partially valid and executed).
This may come as a surprise to users and cause unexpected data loss in rare cases (when using the search to recover mail out of the trash or spam).

To Reproduce
Steps to reproduce the behavior:

1. have access to at least one shared mailbox and the personal mailbox, both with mail in it that can turn up in the same search query
2. search for the mail
3. select all mail that was found
4. try to move the selection to another folder
5. only the mail that is in the target folders mailbox gets moved.

Expected behavior
The least surprising behavior would probably be to actually move all mail into the target folder. This is currently not easily possible.
The second least surprising option may be to deactivate the move action for such selection. This option may cause frustration because it's hard to separate mail in different mailboxes when looking at the search result.

Additional context
This issue has a counterpart when modifying labels on mail in a search result. we should take care to be consistent here.