[MlMt] Moving large IMAP folders

[Kee Hinckley]

> On Jan 11, 2014, at 2:31 AM, "Bill Cole" <mmlist-20120120 at billmail.scconsult.com> wrote:
> 
>> On 3 Jan 2014, at 14:04, Benny Kjær Nielsen wrote:
>> 
>>> On 3 Jan 2014, at 17:08, Kee Hinckley wrote:
>>> 
>>> Is there in fact an underlying IMAP command to move a folder hierarchy (as opposed to rename)? Or if I tell MailMate to move a folder, is it going to copy and delete?
>> 
>> It is going to be copy and delete. Many servers though do that just as efficiently as if it was a move (but not all servers).
> 
> Does the IMAP RENAME command not actually work reliably to move folders and their children? http://tools.ietf.org/html/rfc3501#section-6.3.5 seems to say it should.

I ran into an issue with this the other day and meant to comment on it.

Apparently IMAP folders aren't really hierarchical in a true sense, so if you rename a folder and expect it to do what a directory does when you rename it (have all the same folders under it, not just the immediate files (messages)) you have to change the path of each folder.

Mailmate's rename is only renaming the top-level folder and not telling IMAP to rename those under it. So you end up with the top level folder having a new name, but all the folder children still having the old path.

I can't think of any case where that's the preferred behavior. I know the recursive rename is the default in my webmail. I ended up going there to rename my folder.

(The efficiency issue is a separate one. I can imagine that if MailMate issues the rename, it could be smart enough to know that all it has to do locally is move the messages. I don't know I'd it does, I imagine that logic could get tricky.)