new calendar entry have a wrong time (2 hours later) with EWS & outlook for mac (clients, who sends specified timezone)

[dominikde]

Hi,

I am using outlook for Mac (Version 16.91.1) and when I add a new calendar entry, for example 14:00 german time (2pm), the calendar entry will be created with a wrong start and end time: 2 hours later! So you will see the meeting in the web interface starting at 16:00h (4pm) German time.

The timezone is correct on server and client. And when I use outlook for windows (same account), or active sync: all is correct. So I had a look at the XML communication to EWS for the calendar entry:

With the mac-outlook you see a Start Date/Time with value: 14:00+01:00

<t:Start>2024-11-25T14:00:00+01:00</t:Start>
<t:End>2024-11-25T14:30:00+01:00</t:End>

And also there is a new parameter for the StartTimeZone and EndTimeZone:

<t:StartTimeZone Id="W. Europe Standard Time"></t:StartTimeZone>
<t:EndTimeZone Id="W. Europe Standard Time"></t:EndTimeZone>

In the log from gromox I see, that this two TimeZone-URIs are completely ignored (not known from gromox):

ews: unknown field URI 'calendar:StartTimeZone' (ignored)
ews: unknown field URI 'calendar:EndTimeZone' (ignored)

Next I tried with a windows outlook, he uses 13:00 UTC in the XML for the same calendar entry and sends no Start/EndTimeZone-Parameter: 13:00:00Z

<t:Start>2024-11-25T13:00:00Z</t:Start>
<t:End>2024-11-25T13:30:00Z</t:End>

(13:00 UTC is the correct value for 14:00 german time = UTC+1)

Proposed solution: when a newer outlook is sending the parameters StartTimeZone + EndTimeZone (this happens, when a client is sending a explicit timezone), than convert the Start- and End-Time specified by '+' or '-' followed by hours and minutes (here +01:00) to the UTC-Time for further processing:

for example: 14:00:00+01:00 you have to calculate 14:00:00 - 01:00 = 13:00:00Z

Here is also a description from microsoft:
https://learn.microsoft.com/en-us/exchange/client-developer/exchange-web-services/time-zones-and-ews-in-exchange

Thanks a lot,
Dominik

[jengelh]

gromox-2.39-24-g93d9a6a08