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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