I configured hibernation as suggested by Aki, and still nothing. What may i be missing?
I just read again the mails you sent and realized it had nothing to do with hibernation. Sorry about that..
imapc_max_idle_time = 1 days
this is related to imap client, not imap connections. it won't really matter for your issue.
also I note that you have disabled SSL and enabled plaintext authentication over insecure channels, is this intentional? For debug purposes you can use rawlogs feature, which is better for this. SSL/TLS is done via Stunnel
https://doc.dovecot.org/admin_manual/debugging/debugging_rawlog/
In fact, you could use this feature to find out whether outlook even tries to use IMAP IDLE in the first place.
Let me check, it must be a reason to not be working with dovecot, when it was with DBMail, Will check and reply soon,
Aki