[Dovecot] "QUOTA" CAPABILITY keyword advertised incorrectly?

[Mike Brudenell]

Greetings -

I'm having a frustrating time with mail clients not picking up Dovecot's 
QUOTA extension to IMAP.

The problem is that the QUOTA keyword isn't advertised in Dovecot's 
response to a CAPABILITY enquiry until *after* the user has authenticated.

Unfortunately I've yet to find a mail client that issues a CAPABILITY 
request after authenticating.  Instead all do so upon initial connection to 
the IMAP server (and, correctly, again after subsequently initiating a 
STARTTLS session but before authentication).

Not re-querying the CAPABILITY after authentication is correct according to 
the IMAP spec in RFC2060, which says:

    6.1.1.  CAPABILITY Command

    Arguments:  none

    Responses:  REQUIRED untagged response: CAPABILITY

    Result:     OK - capability completed
                BAD - command unknown or arguments invalid

    The CAPABILITY command requests a listing of capabilities that the
    server supports.  The server MUST send a single untagged CAPABILITY
    response with "IMAP4rev1" as one of the listed capabilities before the
    (tagged) OK response.  This listing of capabilities is not dependent
    upon connection state or user.  It is therefore not necessary to issue
    a CAPABILITY command more than once in a connection.

In particular the last two sentences are relevant.  (At present Dovecot is 
only advertising availability of the QUOTA extension *after* 
authentication, and hence *is* dependent on the user.)

Ths means that at present Dovecot's provision of the QUOTA extension isn't 
actually getting used by popular mail clients such as Thunderbird.

Cheers,
Mike Brudenell

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