Re: It's not possible to create folder which name starts with hash-sign (#)

I've been debugging it a bit and I _think_ the problem is with 
`org.apache.james.imap.main.PathConverter#isAbsolute` 
(https://github.com/apache/james-project/blob/master/protocols/imap/src/main/java/org/apache/james/imap/main/PathConverter.java#L60) 
method.

My understanding is that it should check if this is absolute path (i.e. 
`#<namespace>:username:folder`) but because it only checks first character then it also returns 
"true" for simple folder name like "#test".

Maybe using `session.supportMultipleNamespaces() && mailboxName.charAt(0) == 
MailboxConstants.NAMESPACE_PREFIX_CHAR;` would work?

Then I ran into another issue with `org.apache.james.mailbox.model.MailboxPath#assertAcceptable` 
(https://github.com/apache/james-project/blob/master/mailbox/api/src/main/java/org/apache/james/mailbox/model/MailboxPath.java#L222) 
which also does the check.

It was introduced in https://issues.apache.org/jira/browse/MAILBOX-392 / 
https://github.com/linagora/james-project/pull/4168 but the MailboxPath class already has namespace 
/ user / name as separate members so I'm not sure that `name.startsWith("#");` check makes sense (it 
can't be namespace indication as we already have namespace apart)

After modifying `isAbsolute()` and `nameContainsForbiddenCharacters()` it seems to work fine(-ish*).

(* - the LIST after creation gives absolute path: `A7 LIST "" #hashtest11` … * `LIST 
(\HasNoChildren) "." "#private.admin@atlantiscity.#hashtest11"`)

I tried to run tests from Idea but again ran into issues with Scala, so I'll have to figure out 
better way to run them:
```
EventStore is already defined as trait EventStore
trait EventStore {
```

Wojtek

On 22/06/2023 11:01, Wojtek wrote:
> Hi,
> 
> 
> Wojtek
> 
> On 22/06/2023 01:32, Benoit TELLIER wrote:
>> Hello Wojtek,
>>
>> That is because James employs a folder hierarchy where '#' is used to denote a namespace.
> 
> I assumed as much.
> 
>> #private:wojtek:INBOX denotes your inbox on which I would have a shared access.
>> #shared:marketting:INBOX denotes a shared mailbox for the marketting team.
>>
>> I bet you could do: #private:wojtek:#hashtest ?
> 
> Unfortunately not:
> 
> ```
> A4 CREATE #private:admin@atlantiscity:#hashtest
> A4 NO CREATE You can not access a mailbox that does not belong to you
> ```
> 
> [More at the end]
> 
> ( `store.getFolder("#private:" + email + ":#hashtest").create(HOLDS_MESSAGES)` )
> 
> What's weird is that the original exception that made me investigate it didn't have hashtag in the 
> foldername itself:
> ```
> 21:33:47.588 [ERROR] o.a.j.i.p.StatusProcessor - Status failed for mailbox 
> #private:[email protected]:Apple Mail To Do
> org.apache.james.mailbox.exception.MailboxNotFoundException: #private:[email protected]:Apple 
> Mail To Do can not be found
>          at 
> org.apache.james.mailbox.store.StoreMailboxManager.lambda$getMailboxReactive$1(StoreMailboxManager.java:282)
> ```
> 
> 
>> That being said, james have no support for accessing shared mailboxes in IMAP just quite yet. The 
>> usefulness of that addressing scheme is thus limited.
>>
>> IMO we could:
>>   - Drop the #namespace:user:mailbox addressing sheme in IMAP as it is not currently in use...
>>   - Or (lighter) if we can't parse a mailbox path (no : after #) then keep the name as is, IE 
>> support #hashtest
>>   - Review and adopt another addressing sheme that matches those of eg cyrus.
> 
> I'm not sure how other implementations do it (only checked it from the end-user point of view).
> 
> As you mentioned, the namespaces doesn't seem to be directly visible in IMAP, nor it's possible to 
> act on them - they are in the repository ("namespace" column) but that's just about it - LIST only 
> shows effective folder name (i.e. "INBOX" and not "#private:wojtek:INBOX").
> 
> Trying to create mailbox that starts with `#`, be that namespace (#private:admin@atlantiscity:test) 
> or plain folder (#test) name just doesn't work.
> 
> RFC mentiones namespaces (https://datatracker.ietf.org/doc/html/rfc3501#page-19) but the example is 
> about usenet. I'm not sure how they are used in James (especially outside IMAP that you mentioned).
> 
> I couldn't find it in the documentation, but through searching I found:
> https://github.com/apache/james-project/pull/680
> https://issues.apache.org/jira/browse/JAMES-3659
> https://www.mail-archive.com/[email protected]/msg71116.html
> and finally
> https://github.com/apache/james-project/blob/master/server/protocols/jmap-rfc-8621/doc/specs/spec/mail/rights.mdown
> 
> Which seems JMAP focused.
> 
> The concept of shared mailbox/being able to send messages on behalf of someone seems interesting 
> though (at least in our case) usual modus operandi (for example for having support email) is:
> - have dedicated mailbox for support user
> - have ticketing system that ties to that mailbox -- users simply interact via tickets
> 
> 
> 
> 
> 
> Regarding possible solutions - maybe, if not referenced directly in IMAP (i.e. if someone doesn't 
> ask about namespaced mailbox, i.e. in format `#<namespace>:username:folder`) then treat it as 
> "simple folder" and allow hash sign. Alternatively if someone uses full format then try to access 
> shared mailbox? I guess it would be akin your second suggestion or some sort of mix between first 
> and second?
> Though, I'm not sure if there is any IMAP client that could use it so maybe first option - drop it 
> altogether from IMAP - would be better?
> 
> 
> 
> 
> 
> Btw. "#" is reserved in James, but only as a prefix (it works in the middle of the folder name):
> 
> A4 CREATE #private:admin@atlantiscity:test
> A4 NO CREATE You can not access a mailbox that does not belong to you
> 
> A5 CREATE #shared:admin@atlantiscity:test
> A5 NO CREATE You can not access a mailbox that does not belong to you
> 
> A6 CREATE #private:admin@atlantiscity:#hashtest
> A6 NO CREATE You can not access a mailbox that does not belong to you
> 
> A7 CREATE #shared:admin@atlantiscity:#hashtest
> A7 NO CREATE You can not access a mailbox that does not belong to you
> 
> A8 CREATE #private:admin@atlantiscity:bla#hashtest
> A8 NO CREATE You can not access a mailbox that does not belong to you
> 
> A9 CREATE #shared:admin@atlantiscity:bla#hashtest
> A9 NO CREATE You can not access a mailbox that does not belong to you
> 
> A10 CREATE test2
> A10 OK [MAILBOXID (27110)] CREATE completed.
> 
> A12 CREATE #hashtest2
> A12 NO CREATE You can not access a mailbox that does not belong to you
> 
> A13 CREATE bla#hashtest2
> A13 OK [MAILBOXID (27111)] CREATE completed.
> 
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