Questions about SPECIAL-USE IMAP extension

[Joseph Tam]

I'd like to configure my dovecot service to use the IMAP SPECIAL-USE
extension, but have a few questions for those who have used them, or
are knowledgable about its use.  Using this configuration as an example,

        namespace {
                ...
                mailbox xxx {
                        special_use = \Sent
                }
        }

Q1) Am I correct that mail client that don't understand SPECIAL-USE
extentions will behave the same way with repect to outgoing mailbox
storage?

Q2) Will SPECIAL-USE enabled mail clients switch the mailbox used for
outgoing mail from whatever it was using (e.g. "Sent Mail") to the
(new) special-use mailbox "xxx"?

Q3) Will SPECIAL-USE enabled mail clients connecting for the first
time use "xxx" for outgoing mail, auto-creating it if necessary?
Or will "xxx" be used only if the user does not manually configure
a mailbox for this purpose?

Q4) If I have an additional configuration

        mailbox yyy {
                special_use = \Sent
        }

how does it affect Q2, Q3?

Thanks to any who can provide clarity on this.

Joseph Tam <jtam.h...@gmail.com>