Hello,

I'm looking for advices on IMAP config tuning for best user experience with Outlook 365.
I'm currently using dovecot 2.3.4.1 (f79e8e7e4) provided with Debian 10.
One of my users has Outlook 365 and an IMAP mailbox of large size with several folders (more than 3GB).
From time to time as his main inbox folder is growing he can see some problems with its Outlook application.
Sometimes it freezes during mailbox synchronisation, sometimes he can't see new incoming emails.

I wonder if there is some specific workarounds for an up-to-date Outlook in Dovecot or if you can suggests some config setup adjustments (timeouts, idleing ...) to avoid problems in his Outlook.
Most of the config are defaults. But I can provide relevant parts of the config if needed.

I have this workaround activated for a long time:
imap_client_workarounds = delay-newmail

By the way, I also have a big IMAP mailbox. Can't see any server specific problem while connecting with Thunderbird to this Dovecot server.

-- 
Best regards,
Artur