问题
I want use Conversation/Threaded message view in roundcube 1.0.1 but the appropriate button is always disabled.
回答1:
For servers that do not offer THREAD (THREAD=REFERENCES) capability, you can still enable the functionality by using MyRoundcube Plugin imap_threads. Basically, download the plugin, enable it and off you go.
http://myroundcube.com/myroundcube-plugins/imap_threads-plugin
回答2:
IMAP server must support the capability THREAD (THREAD=REFERENCES)
来源：https://stackoverflow.com/questions/23779707/conversation-threaded-message-view-in-roundcube-1-0-1-is-disabled