Upgrade to 4.5 GA as that's now available and check the timezone information again. If you need to change it then change in in the COS with this command:
this command will display the current value:
Code:
zmprov gc default | grep zimbraPrefTimeZoneId
this will change it:
Code:
zmprov mc default zimbraPrefTimeZoneId '(GMT+01.00) Brussels / Copenhagen / Madrid / Paris'
Obviously the timezone should be the one you require.