Re: nnimap subfolder problem

Re: nnimap subfolder problem

[Kevin Hilman]

I followed the this thread via the web archives, and had some
follow-up comments/questions.

I'm just trying to switch Gnus to use Lotus Domino as an IMAP server
(please no flames about Domino, I don't have a choice here.)
Currently I'm happily using Gnus as an IMAP client to a Courier IMAP
server.

Turns out Domino uses a '\' character as it's hierarchy separator
(different from '/' or '.' used by other servers I've seen.)

If I tell Gnus to create folders with the '\' character it works fine,
however as new folders are created, I don't see them when i do a 'B'
(gnus-group-browse-foreign-server).  I can see them in the folder
listing of other clients (like Mozilla) though.  If I do a 'j'
(gnus-group-jump-to-group) and type the full group name (for example
nnimap+mailserver:foo\bar) I can get to it just fine.

So, I have a couple of questions

1) How can the browse-foreign server pick up these folders and
   subfolders?

2) Is there a way Gnus can be smarter about creating subfolders based
   on some existing hierarchy information?

Thanks

--
Kevin Hilman

Re: nnimap subfolder problem

[Simon Josefsson]

Kevin Hilman <khilman@equator.com> writes:

> If I tell Gnus to create folders with the '\' character it works fine,
> however as new folders are created, I don't see them when i do a 'B'
> (gnus-group-browse-foreign-server).  I can see them in the folder
> listing of other clients (like Mozilla) though.  If I do a 'j'
> (gnus-group-jump-to-group) and type the full group name (for example
> nnimap+mailserver:foo\bar) I can get to it just fine.
>
> So, I have a couple of questions
>
> 1) How can the browse-foreign server pick up these folders and
>    subfolders?

It should find them automatically.  Do you see them if you do ^ and
then RET on the IMAP server?  But there may be some quoting problem
since elisp uses \ as a quoting character, and `read' is still used in
some parts of imap.el.  Do you get anything weird in *Messages*?

> 2) Is there a way Gnus can be smarter about creating subfolders based
>    on some existing hierarchy information?

What do you mean?  Gnus doesn't care about the hierarchy delimiter
(and hence the hierarchy), you could use the Topic mode in the Group
buffer to do some hierarchies though.

Re: nnimap subfolder problem

[Kevin Hilman]

Simon Josefsson <jas@extundo.com> writes:

> Kevin Hilman <khilman@equator.com> writes:
> 
> > If I tell Gnus to create folders with the '\' character it works fine,
> > however as new folders are created, I don't see them when i do a 'B'
> > (gnus-group-browse-foreign-server).  I can see them in the folder
> > listing of other clients (like Mozilla) though.  If I do a 'j'
> > (gnus-group-jump-to-group) and type the full group name (for example
> > nnimap+mailserver:foo\bar) I can get to it just fine.
> >
> > So, I have a couple of questions
> >
> > 1) How can the browse-foreign server pick up these folders and
> >    subfolders?
>
> It should find them automatically.  Do you see them if you do ^ and
> then RET on the IMAP server?  

No. If I use '.' or '/' as a separator, it will see those, but not when
using '\' .

> But there may be some quoting problem since elisp uses \ as a
> quoting character, and `read' is still used in some parts of
> imap.el.  Do you get anything weird in *Messages*?

Nothing suspicious in *Messages*

> > 2) Is there a way Gnus can be smarter about creating subfolders based
> >    on some existing hierarchy information?
> 
> What do you mean?  Gnus doesn't care about the hierarchy delimiter
> (and hence the hierarchy), you could use the Topic mode in the Group
> buffer to do some hierarchies though.

For example, in my nnimap-split-rule I use

  ("lists\\ding" "^Sender: owner-ding")

To put ding list messages into ding (a subfolder of 'lists') with '\'
as a separator (note it has to be escaped).

What I'd like is to have Gnus query the separator character from the
server and put it in a variable so I could then use

  ("lists" + gnus-imap-hierarchy-separator + "ding" ....)

To create folders on the server.  (I don't know lisp, so the syntax is
wrong) So it is portable across mail servers.  It took me a while to
figure out that Lotus Domino uses '\' as a separator character.

-- 
Kevin Hilman               ---  Equator Technologies, Inc.
khilman@equator.com        ---  Seattle, WA USA

Re: nnimap subfolder problem

[Simon Josefsson]

Kevin Hilman <khilman@equator.com> writes:

> Simon Josefsson <jas@extundo.com> writes:
>
>> Kevin Hilman <khilman@equator.com> writes:
>> 
>> > If I tell Gnus to create folders with the '\' character it works fine,
>> > however as new folders are created, I don't see them when i do a 'B'
>> > (gnus-group-browse-foreign-server).  I can see them in the folder
>> > listing of other clients (like Mozilla) though.  If I do a 'j'
>> > (gnus-group-jump-to-group) and type the full group name (for example
>> > nnimap+mailserver:foo\bar) I can get to it just fine.
>> >
>> > So, I have a couple of questions
>> >
>> > 1) How can the browse-foreign server pick up these folders and
>> >    subfolders?
>>
>> It should find them automatically.  Do you see them if you do ^ and
>> then RET on the IMAP server?  
>
> No. If I use '.' or '/' as a separator, it will see those, but not when
> using '\' .

Could you frob `imap-log' and send the contents after doing ^ and RET?
Maybe the parser fails.  This should work, thanks for debugging it.

>> > 2) Is there a way Gnus can be smarter about creating subfolders based
>> >    on some existing hierarchy information?
>> 
>> What do you mean?  Gnus doesn't care about the hierarchy delimiter
>> (and hence the hierarchy), you could use the Topic mode in the Group
>> buffer to do some hierarchies though.
>
> For example, in my nnimap-split-rule I use
>
>   ("lists\\ding" "^Sender: owner-ding")
>
> To put ding list messages into ding (a subfolder of 'lists') with '\'
> as a separator (note it has to be escaped).
>
> What I'd like is to have Gnus query the separator character from the
> server and put it in a variable so I could then use
>
>   ("lists" + gnus-imap-hierarchy-separator + "ding" ....)
>
> To create folders on the server.  (I don't know lisp, so the syntax is
> wrong) So it is portable across mail servers.  It took me a while to
> figure out that Lotus Domino uses '\' as a separator character.

The hierarchy separator can change depending on where you are in the
hierarchy, so it would have to be a function.  And that function is
not difficult to write, maybe this works:

(defun jas-get-delimiter (group buffer)
  (with-current-buffer buffer
    (imap-mailbox-list group)
    (imap-mailbox-get 'delimiter group)))

and then use

(setq nnimap-split-rule `(...
   (,(concat "lists" (jas-get-delimiter "lists" nnimap-server-buffer) "ding")
     "^Sender: owner-ding")
   ...))

or something.

Re: nnimap subfolder problem

[Kevin Hilman]

[-- Attachment #1: Type: text/plain, Size: 1294 bytes --]

Simon Josefsson <jas@extundo.com> writes:

> Kevin Hilman <khilman@equator.com> writes:
> 
> > Simon Josefsson <jas@extundo.com> writes:
> >
> >> Kevin Hilman <khilman@equator.com> writes:
> >> 
> >> > If I tell Gnus to create folders with the '\' character it works fine,
> >> > however as new folders are created, I don't see them when i do a 'B'
> >> > (gnus-group-browse-foreign-server).  I can see them in the folder
> >> > listing of other clients (like Mozilla) though.  If I do a 'j'
> >> > (gnus-group-jump-to-group) and type the full group name (for example
> >> > nnimap+mailserver:foo\bar) I can get to it just fine.
> >> >
> >> > So, I have a couple of questions
> >> >
> >> > 1) How can the browse-foreign server pick up these folders and
> >> >    subfolders?
> >>
> >> It should find them automatically.  Do you see them if you do ^ and
> >> then RET on the IMAP server?  
> >
> > No. If I use '.' or '/' as a separator, it will see those, but not when
> > using '\' .
> 
> Could you frob `imap-log' and send the contents after doing ^ and RET?
> Maybe the parser fails.  This should work, thanks for debugging it.

OK, here you go.  Note that there are indeed subfolders of the
'equator' and the 'lists' folders that can be seen from the mozilla
IMAP client just fine.

-kev-


[-- Attachment #2: imap-log contents --]
[-- Type: text/plain, Size: 1788 bytes --]

133 LIST "" "*%"
* LIST () "\\" Drafts
* LIST () "\\" equator
* LIST (\Noinferiors) "\\" INBOX
* LIST () "\\" lists
* LIST () "\\" Sent
* LIST () "\\" Trash
133 OK LIST completed
134 EXAMINE "INBOX"
* 9 EXISTS
* 0 RECENT
* OK [UIDVALIDITY 4] UIDs valid
* FLAGS (\Flagged \Seen \Answered \Deleted \Draft)
* OK [PERMANENTFLAGS ()] Permanent flags
134 OK [READ-ONLY] EXAMINE completed
135 FETCH 1,* UID
* 1 FETCH (UID 62)
* 9 FETCH (UID 649)
135 OK FETCH completed
136 EXAMINE "Drafts"
* 0 EXISTS
* 0 RECENT
* OK [UIDVALIDITY 16] UIDs valid
* FLAGS (\Flagged \Seen \Answered \Deleted \Draft)
* OK [PERMANENTFLAGS ()] Permanent flags
136 OK [READ-ONLY] EXAMINE completed
137 EXAMINE "Trash"
* 1 EXISTS
* 0 RECENT
* OK [UIDVALIDITY 5] UIDs valid
* FLAGS (\Flagged \Seen \Answered \Deleted \Draft)
* OK [PERMANENTFLAGS ()] Permanent flags
137 OK [READ-ONLY] EXAMINE completed
138 FETCH 1,* UID
* 1 FETCH (UID 9)
138 OK FETCH completed
139 EXAMINE "equator"
* 57 EXISTS
* 0 RECENT
* OK [UNSEEN 57] Message 57 is first unseen
* OK [UIDVALIDITY 28] UIDs valid
* FLAGS (\Flagged \Seen \Answered \Deleted \Draft)
* OK [PERMANENTFLAGS ()] Permanent flags
139 OK [READ-ONLY] EXAMINE completed
140 FETCH 1,* UID
* 1 FETCH (UID 2)
* 57 FETCH (UID 65)
140 OK FETCH completed
141 EXAMINE "lists"
* 0 EXISTS
* 0 RECENT
* OK [UIDVALIDITY 29] UIDs valid
* FLAGS (\Flagged \Seen \Answered \Deleted \Draft)
* OK [PERMANENTFLAGS ()] Permanent flags
141 OK [READ-ONLY] EXAMINE completed
142 EXAMINE "Sent"
* 15 EXISTS
* 0 RECENT
* OK [UNSEEN 3] Message 3 is first unseen
* OK [UIDVALIDITY 17] UIDs valid
* FLAGS (\Flagged \Seen \Answered \Deleted \Draft)
* OK [PERMANENTFLAGS ()] Permanent flags
142 OK [READ-ONLY] EXAMINE completed
143 FETCH 1,* UID
* 1 FETCH (UID 2)
* 15 FETCH (UID 16)
143 OK FETCH completed

Re: nnimap subfolder problem

[Amos Gouaux]

>>>>> On Tue, 16 Oct 2001 20:12:58 +0200,
>>>>> Simon Josefsson <jas@extundo.com> (sj) writes:

sj> You are right, but I think it is hard to use it in any useful way, the
sj> hierarchy delimiter can change between hierarchies.  For example, just
sj> because you know that `.' is used to delimiter "INBOX" from "private"
sj> doesn't mean you know anything about the delimiter used below
sj> "private".  (You could replace "INBOX" with "~" and "private" with
sj> "mail" for a UoW example.)

Can you really change the delimiter like this?  Never thought about
it before, but I guess so.  Though, I'd be surprised if many clients
could cope with this.  Hell, I've seen too many clients make blind
assumptions as to what the delimiter should be as it is.

Perhaps just check with the INBOX and then ass-u-me that it's that
way for the entire folder space?  Perhaps just document that as the
current limitation?  Would there really be anybody that found this
to be a problem?  Are there even any servers that allow the
delimiter to change in the folder space like this?



-- 
Amos

Re: nnimap subfolder problem

[Steinar Bang]

>>>>> Nicolas KOWALSKI <Nicolas.Kowalski@imag.fr>:

> Hello.

> At work, I use the nnimap backend, which "talks" to an UW-imapd
> server.
[snip!]
> My problem is : when I try to rename (G r) the group "perso/famille"
> to something like "perso/famille/misc", Gnus tells me the group has
> an invalid name...I suspect Gnus to not tolerate '/' characters in
> group names, but that is what I need in my case.

> Any idea(s) ?

Whether you can make subfolders of existing folders in UoW imapd,
depends on the folder format used by the imapd.

The UNIX mbox format, which used to be the default folder format of
UoW imapd (I don't know if it still is), does not support subfolders.

Re: nnimap subfolder problem

[Simon Josefsson]

Kai.Grossjohann@CS.Uni-Dortmund.DE (Kai Großjohann) writes:

> Simon Josefsson <jas@extundo.com> writes:
> 
>> Right, but there is no generic connection between directories and the
>> delimiter character used in group names with IMAP.
> 
> I vaguely recall that there is an IMAP protocol element where you can
> ask the server which character it uses as a hierarchy delimiter.  Am I
> dreaming?

You are right, but I think it is hard to use it in any useful way, the
hierarchy delimiter can change between hierarchies.  For example, just
because you know that `.' is used to delimiter "INBOX" from "private"
doesn't mean you know anything about the delimiter used below
"private".  (You could replace "INBOX" with "~" and "private" with
"mail" for a UoW example.)

Of course, please prove me wrong.

Re: nnimap subfolder problem

[Nicolas KOWALSKI]

Kai.Grossjohann@CS.Uni-Dortmund.DE (Kai Großjohann) writes:

> Simon Josefsson <jas@extundo.com> writes:
> 
>> Right, but there is no generic connection between directories and the
>> delimiter character used in group names with IMAP.
> 
> I vaguely recall that there is an IMAP protocol element where you can
> ask the server which character it uses as a hierarchy delimiter.  Am I
> dreaming?

Mmh. I was wrong in my last post :

7.2.2.  LIST Response

   Contents:   name attributes
               hierarchy delimiter
               name

      The LIST response occurs as a result of a LIST command.  It
      returns a single name that matches the LIST specification.  There
      can be multiple LIST responses for a single LIST command.

<snip>

      The hierarchy delimiter is a character used to delimit levels of
      hierarchy in a mailbox name.  A client can use it to create child
      mailboxes, and to search higher or lower levels of naming
      hierarchy.  All children of a top-level hierarchy node MUST use
      the same separator character.  A NIL hierarchy delimiter means
      that no hierarchy exists; the name is a "flat" name.

      The name represents an unambiguous left-to-right hierarchy, and
      MUST be valid for use as a reference in LIST and LSUB commands.
      Unless \Noselect is indicated, the name MUST also be valid as an
            argument for commands, such as SELECT, that accept mailbox
      names.

   Example:    S: * LIST (\Noselect) "/" ~/Mail/foo



Nicolas.

Re: nnimap subfolder problem

[Nicolas KOWALSKI]

Simon Josefsson <jas@extundo.com> writes:

> 
> But if you used the Cyrus IMAPD server, all your users would be
> creating mailboxes containing `.' for hierarchies instead. :-)
> 

Argh... :-).


> My point is, the hierarchy delimiter is not agreed on, and with IMAP
> it may even change between each hierarchy (you could e.g. have a
> mailbox called foo.bar/baz#boo&apa and each of the characters could be
> "real" hierarchy delimiters).

No no. The RFC says :

5.1.1.  Mailbox Hierarchy Naming

   If it is desired to export hierarchical mailbox names, mailbox names
   MUST be left-to-right hierarchical using a single character to
   separate levels of hierarchy.  The same hierarchy separator character
   is used for all levels of hierarchy within a single name.


> I'm not sure how this could be implemented, suggestions welcome.

I also searched the RFC for something like "what's your delimiter ?",
but it does not seem to be supported. Sigh.

I will look forward.

Thanks for your answers.
Nicolas.

Re: nnimap subfolder problem

[Kai Großjohann]

Simon Josefsson <jas@extundo.com> writes:

> Right, but there is no generic connection between directories and the
> delimiter character used in group names with IMAP.

I vaguely recall that there is an IMAP protocol element where you can
ask the server which character it uses as a hierarchy delimiter.  Am I
dreaming?

kai
-- 
Linux provides a nice `poweroff' command, but where is `poweron'?

Re: nnimap subfolder problem

[Simon Josefsson]

Nicolas KOWALSKI <Nicolas.Kowalski@imag.fr> writes:

>> But with nnimap, the directories and files exists on the server, so
>> Gnus has no control of how they are named other than by replacing `.'
>> with `/' in the group name but that would be confusing, I think.
> 
> Confusing ? This is the standard behaviour for nnml and
> nnfolder. The first time is used those (as well as Gnus actually), I
> was confused. But then, I thought this storage using subdirectories
> was the best method.

Right, but there is no generic connection between directories and the
delimiter character used in group names with IMAP.  With the UoW
server `/' is used as the directory delimiter, with Cyrus IMAPD `.'
is used, and other servers may have other delimiters as well.

Also, compare with NNTP, Gnus doesn't do anything about hierarchies
there, it is up to the server to decide what to export.  Nnimap is
more similar to nntp than nnml/nnfolder.

>> I think everything would work fine if you create a group with a dot in
>> its name using another client (I do this all the time).  What problems
>> do you see?
> 
> I agree there are no problems. 
> 
> That just a question of habits and to make nnimap behave more like
> nnml/nnfolder backends. In addition to this, I have never seen some of
> our users use dot-named folders with their IMAP clients ; they always
> prefer to create subfolders hierarchies, as I do (until now,
> perhaps).

But if you used the Cyrus IMAPD server, all your users would be
creating mailboxes containing `.' for hierarchies instead. :-)

My point is, the hierarchy delimiter is not agreed on, and with IMAP
it may even change between each hierarchy (you could e.g. have a
mailbox called foo.bar/baz#boo&apa and each of the characters could be
"real" hierarchy delimiters).

I'm not sure how this could be implemented, suggestions welcome.

Re: nnimap subfolder problem

[Nicolas KOWALSKI]

Simon Josefsson <jas@extundo.com> writes:

> 
> But with nnimap, the directories and files exists on the server, so
> Gnus has no control of how they are named other than by replacing `.'
> with `/' in the group name but that would be confusing, I think.
> 

Confusing ? This is the standard behaviour for nnml and
nnfolder. The first time is used those (as well as Gnus actually), I
was confused. But then, I thought this storage using subdirectories
was the best method.


> I think everything would work fine if you create a group with a dot in
> its name using another client (I do this all the time).  What problems
> do you see?

I agree there are no problems. 

That just a question of habits and to make nnimap behave more like
nnml/nnfolder backends. In addition to this, I have never seen some of
our users use dot-named folders with their IMAP clients ; they always
prefer to create subfolders hierarchies, as I do (until now, perhaps).


> Or were you talking about the NOV cache?  It could translate `.' into
> `/' but I don't see the point, there would only be one file in most
> directories anyway, wouldn't it?

No point here.

> 
> Translating `.' into `/' is only something you need if your filesystem
> is 8+3 or similar and can't store e.g. "foo.bar.baz", isn't it?  I
> haven't seen any IMAP server that has this problem.

I agree.

Nicolas.

Re: nnimap subfolder problem

[Simon Josefsson]

Nicolas KOWALSKI <Nicolas.Kowalski@imag.fr> writes:

>>> PS 2: when I use nnml or nnfolder backends, Gnus stores groups using
>>> subdirectories for group names like "foo.bar.geez" (gives
>>> foo/bar/geez). Is it possible to use the same functionnality for
>>> nnimap backend ?
>> 
>> I don't think so, it would mean making `.' and `/' equivalent, and
>> that is something the IMAP server should do (if at all).
> 
> I disagree : what happens if our Eudora/Messenger/Outlook users
> create folders containing dot in their names ? The Gnus beahviour to
> create subfolders with dot-named folders is Gnus specific, ans
> should stays IMHO as is.

But with nnimap, the directories and files exists on the server, so
Gnus has no control of how they are named other than by replacing `.'
with `/' in the group name but that would be confusing, I think.

I think everything would work fine if you create a group with a dot in
its name using another client (I do this all the time).  What problems
do you see?

Or were you talking about the NOV cache?  It could translate `.' into
`/' but I don't see the point, there would only be one file in most
directories anyway, wouldn't it?

Translating `.' into `/' is only something you need if your filesystem
is 8+3 or similar and can't store e.g. "foo.bar.baz", isn't it?  I
haven't seen any IMAP server that has this problem.

Re: nnimap subfolder problem

[Nicolas KOWALSKI]

Simon Josefsson <jas@extundo.com> writes:

>> 
>> My problem is : when I try to rename (G r) the group "perso/famille"
>> to something like "perso/famille/misc", Gnus tells me the group has an
>> invalid name...I suspect Gnus to not tolerate '/' characters in group
>> names, but that is what I need in my case.
>> 
>> Any idea(s) ?
> 
> You need to customize the variable below.  Does anyone know why `/'
> was forbidden in group names?  Maybe we can change the default?
> 
> `gnus-invalid-group-regexp'

Ok, worked fine. Thanks a lot.

> 
>> PS : I tried to rename "perso/famille" to "perso.famille", this works;
>>      but then I can not rename it to use subfolders 
>>      ("perso/famille/misc").
> 
> Why not?  Creating a file perso.famille.misc should work fine, even if
> there is a perso.famille file.  Perhaps this approach is the easist.
> 

I already thought this approach was easy. This is just a question of
habits :-|.


>> PS 2: when I use nnml or nnfolder backends, Gnus stores groups using
>> subdirectories for group names like "foo.bar.geez" (gives
>> foo/bar/geez). Is it possible to use the same functionnality for
>> nnimap backend ?
> 
> I don't think so, it would mean making `.' and `/' equivalent, and
> that is something the IMAP server should do (if at all).

I disagree : what happens if our Eudora/Messenger/Outlook users create
folders containing dot in their names ? The Gnus beahviour to create
subfolders with dot-named folders is Gnus specific, ans should stays
IMHO as is.

Nicolas.

Re: nnimap subfolder problem

[Simon Josefsson]

Nicolas KOWALSKI <Nicolas.Kowalski@imag.fr> writes:

> Hello.
> 
> At work, I use the nnimap backend, which "talks" to an UW-imapd
> server. My folders are stored using subfolders, like the following:
> 
>   [ Misc -- 0 ]
>         0: INBOX
>         0: mail/drafts
>         0: mail/sent
>         0: mail/templates
>   [ Personal -- 0 ]
>         0: perso/famille
>         0: perso/misc
>   [ VERIMAG -- 0 ]
>         0: verimag/hardware
> 
> 
> My problem is : when I try to rename (G r) the group "perso/famille"
> to something like "perso/famille/misc", Gnus tells me the group has an
> invalid name...I suspect Gnus to not tolerate '/' characters in group
> names, but that is what I need in my case.
> 
> Any idea(s) ?

You need to customize the variable below.  Does anyone know why `/'
was forbidden in group names?  Maybe we can change the default?

`gnus-invalid-group-regexp'
     Regexp to match "invalid" group names when querying user for a
     group name.  The default value catches some *really* invalid group
     names who could possibly mess up Gnus internally (like allowing
     `:' in a group name, which is normally used to delimit method and
     group).

     IMAP users might want to allow `/' in group names though.

> PS : I tried to rename "perso/famille" to "perso.famille", this works;
>      but then I can not rename it to use subfolders 
>      ("perso/famille/misc").

Why not?  Creating a file perso.famille.misc should work fine, even if
there is a perso.famille file.  Perhaps this approach is the easist.

> PS 2: when I use nnml or nnfolder backends, Gnus stores groups using
> subdirectories for group names like "foo.bar.geez" (gives
> foo/bar/geez). Is it possible to use the same functionnality for
> nnimap backend ?

I don't think so, it would mean making `.' and `/' equivalent, and
that is something the IMAP server should do (if at all).

nnimap subfolder problem

[Nicolas KOWALSKI]

Hello.

At work, I use the nnimap backend, which "talks" to an UW-imapd
server. My folders are stored using subfolders, like the following:

  [ Misc -- 0 ]
        0: INBOX
        0: mail/drafts
        0: mail/sent
        0: mail/templates
  [ Personal -- 0 ]
        0: perso/famille
        0: perso/misc
  [ VERIMAG -- 0 ]
        0: verimag/hardware


My problem is : when I try to rename (G r) the group "perso/famille"
to something like "perso/famille/misc", Gnus tells me the group has an
invalid name...I suspect Gnus to not tolerate '/' characters in group
names, but that is what I need in my case.

Any idea(s) ?

Thanks in advance,
Nicolas.

PS : I tried to rename "perso/famille" to "perso.famille", this works;
     but then I can not rename it to use subfolders 
     ("perso/famille/misc").

PS 2: when I use nnml or nnfolder backends, Gnus stores groups using
subdirectories for group names like "foo.bar.geez" (gives
foo/bar/geez). Is it possible to use the same functionnality for
nnimap backend ?