When user create an all day event from webmail with below .ics file added to outlook eas account. The event received in the attendee/setup account in outlook through eas having all day covering two days.

Question

When user create an all day event from webmail/with below ics file to outlook eas account. The event received in the attendee account setup in outlook through eas having all day event from 1:00am to 12:00am covering two days. Verified the option of Time zone of outlook desktop

attached supporting images options of desktop outlook.png and desktop outloook cal.png

issue is with outlook desktop version and same ics file added in outlook does not have same scenario it works correctly in web outlook

please find the below .ics file replaced attenders name with *********

BEGIN:VCALENDAR

VERSION:2.0

PRODID:-//Sabre//Sabre VObject 4.5.4//EN

CALSCALE:GREGORIAN

METHOD:REQUEST

BEGIN:VTIMEZONE

TZID:Asia/Kolkata

X-LIC-LOCATION:Asia/Kolkata

BEGIN:STANDARD

DTSTART:18800101T000000

RDATE:18800101T000000

TZNAME:HMT

TZOFFSETFROM:+055328

TZOFFSETTO:+055320

END:STANDARD

BEGIN:STANDARD

DTSTART:19411001T000000

RDATE:19411001T000000

TZNAME:BURT

TZOFFSETFROM:+055320

TZOFFSETTO:+0630

END:STANDARD

BEGIN:STANDARD

DTSTART:19420515T000000

RDATE:19420515T000000

RDATE:19451015T000000

TZNAME:IST

TZOFFSETFROM:+0630

TZOFFSETTO:+0530

END:STANDARD

BEGIN:STANDARD

DTSTART:19420901T000000

RDATE:19420901T000000

TZNAME:IST

TZOFFSETFROM:+0530

TZOFFSETTO:+0630

END:STANDARD

END:VTIMEZONE

BEGIN:VEVENT

SUMMARY:all day task

ATTENDEE;CN=*********;PARTSTAT=ACCEPTED:mailto:*********

ATTENDEE;CN=*********;PARTSTAT=NEEDS-ACTION:mailto:*********

ATTENDEE;CN=*********;PARTSTAT=NEEDS-ACTION:mailto

:*********

LAST-MODIFIED:20240717T130312Z

SEQUENCE:0

DTSTART;VALUE=DATE:20240921

DTEND;VALUE=DATE:20240922

UID:BD3D21B2-E7E9-4689-B141-E5BE8BA7F3A6

DTSTAMP:20240717T130313Z

ORGANIZER;PARTSTAT=ACCEPTED;CN=*********:mailto:*********

END:VEVENT

END:VCALENDAR

Answer 1

Hi,Welcome to the Microsoft Q&A forum!

When a request is received to create a new all-day event with non-midnight (in the time zone of the request or appointment) start and/or end times, those times get adjusted to midnight in the appropriate time zone according to the following rules:

• Non-midnight start times are adjusted to the midnight prior to the time specified. For example, 1:00 PM on June 6 gets adjusted to 12:00 AM on June 6.
• Non-midnight end times are adjusted to the midnight after the time specified. For example, 1:00 PM on June 6 gets adjusted to 12:00 AM on June 7.

So the all-day event that you create is always inclusive of the start and end time that you specify, but might claim additional time on the user's calendar due to the shift to midnight. Because the server will adjust the start and end time to midnight, we recommend that you specify your start and end time at midnight to avoid any unintended changes to the times.

You can refer to:https://learn.microsoft.com/en-us/exchange/client-developer/exchange-web-services/how-to-create-all-day-events-by-using-ews-in-exchange?source=recommendations

Please feel free to contact me for any updates. And don't forget to mark it as an answer if this helps.