Huge number of IMAP sessions

[Asterix]

As RoundCube is performing an separate IMAP session per concurrent user every 30 seconds, this puts an large strain on the IMAP server which is not really necessary in my opinion.

Has anyone fixed or a work-around for this? I assume that setting Keep-Alive higher does not make any difference. And using the IMAP IDLE command?

Is anyone using a separate IMAP proxy application? If so, which one?

Kind regards,

Marcel