Explanation of the messages:

imaplogin: DISCONNECTED, ip=[::ffff:127.0.0.1], time=25

This connection to the IMAP server has been closed without
login.

imaplogin: DISCONNECTED, user=racke@linuxia.de, ip=[::ffff:127.0.0.1], headers=0, body=0, time=17

This connection to the IMAP server has been closed.