My customer got:
IMAP server closed the connection. This can occur if you leave the
connection idle for too long.

Account: ..... IMAP4rev1 server terminating connection.
Protocol: IMAP
Server: 192.168.x.x
Port: 143
Error Code: 0x800CCCDD.

Timeout configured n outlook is the max allowed: 10 minutes. This happen before 10 minutes of inactivity.