since Zarafa, we are using an external mailarchiv. It will authenticate via a copied version of kopano-gateway.service, started with another konfig ("-F /etc/kopano/gateway-nopass") on another port with option “bypass_auth = yes” and another log-file.
After about one week working without problems, the log will tell me:
Fri Dec 29 16:00:06 2017: [error ]  M4LMsgServiceAdmin::ConfigureMsgService() MSGServiceEntry failed 80040111: logon failed Fri Dec 29 16:00:06 2017: [crit ]  CreateProfileTemp(): ConfigureMsgService failed 80040111: logon failed Fri Dec 29 16:00:06 2017: [warning]  CreateProfileTemp failed: 80040111: logon failed Fri Dec 29 16:00:06 2017: [warning]  Failed to login from <ip>:46726 with invalid username "mailarchiv" or wrong password. Error: 0x80040111
i need to restart the service that everything is fine again. - But why does it even try to check username and/or password?
There was an update in the past where this option (bypass_auth) was updated or implemented. it was around this time the error occured once.
i’ve turned on the Info-Logging and will try to deliver more informations.