[horde] PHP IMAP Library - Accessing shared mailbox

[Dax]

Dear Horde people,

Recently, I have found it useful to use shared mailboxes.

The standard way of accessing shared mailboxes is not working with the
Horde IMAP PHP library. The method is as follows;

username = user at domain.com\sharedmailboxalias
password = userpassword

This method works with Thunderbird and Python's IMAPClient library, but not
with Horde IMAP PHP library. I looked through the source code and tried
many things, such as changing the encoding of the username and escaping the
 backslash character, nothing worked.

The error is: exception 'Horde_Imap_Client_Exception' with message 'Mail
server denied authentication.'

Have any of you gotten this to work?

Is there something I'm doing wrong or missing? If not, when will this
feature be available in the Horde IMAP library?

Thank you for your time & kind regards,
Dax