[Dovecot] Active IMAP sessions per server?

Hi,

I'm curious about some of the larger dovecot installs out there and what your current active user load looks like per server. Realistically, how many active IMAP sessions are some of you maintaining? At what point did you find the load became unmanageable? I know there's a lot of different factors involved in this, but I'm just looking to get a rough idea of what I can expect to be able to handle with dovecot.

Any help is appreciated

Regards, Brent