Thanks for your reply and sorry for not having opened an issue on GitHub!
I’ve started another test with an empty calendar.
Here is the complete ics file:
BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//Kopano//11.0.2//EN
CALSCALE:GREGORIAN
METHOD:PUBLISH
BEGIN:VEVENT
TRANSP:TRANSPARENT
X-MICROSOFT-CDO-INTENDEDSTATUS:FREE
CREATED:20220908T213511Z
LAST-MODIFIED:20220908T213511Z
DTSTAMP:20220908T213511Z
DTSTART;VALUE=DATE:20220911
DTEND;VALUE=DATE:20220912
SUMMARY:appointment test 2022-09-12\, all day
PRIORITY:5
CLASS:PUBLIC
UID:
040000008200E00074C5B7101A82E00800000000800564E4CAC3D801000000000000000001
00000035A1B8102AFD4AE9AC9D0C575AFC4F57
X-MICROSOFT-CDO-OWNER-CRITICAL-CHANGE:20220908T213519Z
X-MICROSOFT-CDO-ATTENDEE-CRITICAL-CHANGE:20220908T213519Z
X-MICROSOFT-CDO-APPT-SEQUENCE:0
X-MICROSOFT-CDO-OWNERAPPTID:-1
X-MICROSOFT-CDO-ALLDAYEVENT:TRUE
END:VEVENT
END:VCALENDAR
The all day event was created with Kopano WebApp for 2022/09/12 and is correctly shown there.
It is also correctly synchronized to my iPhone via z-push / ActiveSync.
I can confirm that all timezones (Debian / MariaDB / z-push / Kopano) are properly set to “Europe/Berlin”.
Thanks for your help and best regards,
David