RFC 2193 (rfc2193) - Page 3 of 9
IMAP4 Mailbox Referrals
Alternative Format: Original Text Document
RFC 2193 IMAP4 Mailbox Referrals September 1997
Example:
A001 NO [REFERRAL IMAP://user;AUTH=*@SERVER2/REMOTE]Remote Mailbox
NOTE: user;AUTH=* is specified as required by [RFC-2192] to avoid a
client falling back to anonymous login.
Remote mailboxes and their inferiors, that are accessible only via
referrals SHOULD NOT appear in LIST and LSUB responses issued against
the user's home server. They MUST appear in RLIST and RLSUB
responses issued against the user's home server. Hierarchy referrals,
in which a client would be required to connect to the remote server
to issue a LIST to discover the inferiors of a mailbox are not
addressed in this document.
For example, if shared mailboxes were only accessible via referrals
on a remote server, a RLIST "" "#SHARED/%" command would return the
same response if issued against the user's home server or the remote
server.
Note: Mailboxes that are available on the user's home server do not
need to be available on the remote server. In addition, there may be
additional mailboxes available on the remote server, but they will
not accessible to the client via referrals unless they appear in the
LIST response to the RLIST command against the user's home server.
A MAILBOX-REFERRALS capable client will issue the RLIST and RLSUB
commands in lieu of LIST and LSUB. The RLIST and RLSUB commands
behave identically to their LIST and LSUB counterparts, except remote
mailboxes are returned in addition to local mailboxes in the LIST and
LSUB responses. This avoids displaying to a non MAILBOX-REFERRALS
enabled client inaccessible remote mailboxes.
4.1. SELECT, EXAMINE, DELETE, SUBSCRIBE, UNSUBSCRIBE, STATUS and APPEND
Referrals
An IMAP4 server MAY respond to the SELECT, EXAMINE, DELETE,
SUBSCRIBE, UNSUBSCRIBE, STATUS or APPEND command with one or more
IMAP mailbox referrals to indicate to the client that the mailbox is
hosted on a remote server.
When a client processes an IMAP mailbox referral, it will open a new
connection or use an existing connection to the remote server so that
it is able to issue the commands necessary to process the remote
mailbox.
Gahrns Standards Track