Ok, I tried the following:
I changed the default COS timezone with:
And created a new COS WesternEurope with timezone:
zmprov mc default zimbraPrefTimeZoneId "(GMT+10.00) Canberra / Melbourne / Sydney"
I have one user with the default COS which creates a calendar invitation for 5PM. When I login to the account of the with the WesternEurope COS I'd expect to see this invite for 8 or 9 AM in the morning (depending if Zimbra would consider daylight savings), however the invite just shows up as 5PM.
zmprov mc WesternEurope zimbraPrefTimeZoneId "(GMT+01.00) Amsterdam / Berlin / Bern / Rome / Stockholm / Vienna"
Any idea what I'm doing wrong?