It happens twice after a reboot and then not anymore and doesn’t seem to have any other side effects. @bhavin your “solution” doesn’t work. In fact if you do have multiple virtual domains, you will break that configuration by removing the others. It doesn’t look the issue is postfix related. It looks more to me like an issue of the kopano-server service not yet being available in time. Might be solved by setting a longer timeout for the kopano-spooler service somewhere?
Just upgraded from 8.3.4 to 8.4.3 latest. I don’t recall seeing this error before.
no such “virtual” folders are currently not supported. Based on customer feedback we are currently investigating mechanisms to open shared calendars through separate accounts (without the need to know the users credentials of course) as part of https://jira.kopano.io/browse/KOE-124.