Changing IMAP separator - does it break things?

[Markus Winkler]

On 14.10.20 15:02, Victor Sudakov wrote:
> I was asking because the section "Hierarchy separators" in
> https://doc.dovecot.org/configuration_manual/namespace/ somewhat implies
> that
> 
> However, changing the separator doesn’t change the on-disk “layout separator”.
> 
> That's why I thought that the separator is in fact virtual.

You're right - please see my former mail and the link you repeated above. 
There's a nice table which shows the possible combinations of hierarchy 
separator (called 'NS sep' there) and 'Layout sep' (structure on disk) and 
the respective results for 'Mailbox name' and the directory structure in 
the filesystem.

> At present, if my folder layout in the mail client is
> 
> Inbox
>    |
>    +---Friends
>           |
>           +----Paul
>           |
>           +----Jessica
> 


> the folder "Jessica" on-disk is something like ~/Maildir/.Friends.Jessica/{cur,new,tmp}/
-------------------------------------------------^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Then you have configured a Layout sep '.' (mail_location = maildir:~/Maildir).


This says nothing about your hierarchy separator, which is controlled by 
the parameter 'separator ='.


> Do you mean to say that if I change the IMAP separator to "/", Dovecot
> will not translate "/" into "." and the folder "Jessica" will become
> inaccessible?

If you currently have 'separator = .' then of course the hierarchy 
separator is '.'. If you change that to 'separator = /' normally the access 
to "Jessica" is still possible.

But (as you can see in the table mentioned above) the name of the mailbox 
(= folder) from the IMAP clients point of view is now 'Friends/Jessica'.

Before the change and with 'separator = .' the name of the mailbox was 
'Friends.Jessica'.

If you telnet to Dovecot and (after authentication) type something like this:

a LIST "" "*"

The server may responds with:

* LIST (\HasChildren) "." INBOX

Here you can see, that this name space has a '.' as the hierarchy separator.

If the response is this:

* LIST (\HasChildren) "/" INBOX

then we know that '/' is the hierarchy separator.


So, if you have an IMAP client which ist standard-compliant he will check 
what's the configured hierarchy separator and will use it for accessing the 
folder structure. And again: this has nothing to do with the on disk 
structure of the folders.

Regards,
Markus