'doveadm who' behind nginx mail proxy

[Edgaras Lukoševičius]

Hello,

we have configured nginx to work as mail proxy for backend dovecot 
servers. Dovecot servers behind nginx proxy are showing internal nginx 
ip address for every client when running 'doveadm who' instead of 
showing real client IP addresses.

Is is possible to configure this setup to show real client IP addresses 
when running 'doveadm who' on internal dovecot servers or to configure 
nginx to show which user-ip pairs are proxied to which servers?