I am sending .ics Datein for this I use the time stamp in the ISO 8601 standard.
DTSTART:20161014T210013+2 DTEND:20161014T213013+2
and for google mail/calendar this is totally fine but Outlook misjudges this as
Mo 01.01.1601 1:00 - 1:00
I can't only send the time without timezone information, because my software has to run on an server and has to work in several different countries. So the timestamp which I get from the user input has to contain that information.
Does anyone have a suggestion?
You need to convert into UTC and add a 'Z' suffix to your datetime (e.g. 20161014T230013Z) so that the client that this is a date with UTC time. See https://www.rfc-editor.org/rfc/rfc5545#section-3.3.5