Dovecot as transparent proxy for Exchange<->Dovecot<->Yahoo.com/Yandex.com with mail synchronization between servers !

We have Exchange as internal mail server, also we have gate where we plant to install Dovecot, also we have external mail at servers such as yahoo.com ort yandex.com. There are some mailboxes at Exchange, for example: us...@internal.ltd to use...@internal.ltd. There are some mailboxes at

[Dovecot] Thread sorting problem

Hi. How much may implementing of THREAD=ORDEREDSUBJECT to Dovecot 2.1.x or later cost ? Artyom.