POP3/IMAP proxy support for XCLIENT/ID

[Chris Adams]

I am setting up an nginx SMTP proxy and using XCLIENT to get the real
client info to the backend Postfix servers.  I'm interested in also
using it for POP3 and IMAP to backend Dovecot servers - it looks like
Dovecot supports XCLIENT in POP3 and ID in IMAP to pass the same real
info.  Is there any support from nginx for that?
-- 
Chris Adams <linux at cmadams.net>