caldav/sabredav disable notification about changed events

Hi all,

I've a question to those, who are familiar with caldav/sabredav. Which
software component is responsible to send notifications about changed
cancelled events?

So far I thought this is only wallace. But wallace isn't involved if the
chages does't result from a itip message inside an email but if event is
changed directly via caldav (e.g. through an caldav client).

How is the mailflow in this case? The itip notifications came from imap
server in this case. But the sabredav component is running on the
webmail server (we have imap, smtp, roundcube on separate hosts).

In roundcube, while editing events, we can configure not to send
notifications.

Now we have here a kind of automatic processing of events(with
vdirsyncer - we use this to schedule an phone system). For these events
we wan't do disable notifications. But I don't find any possibility.

It doesn't seem to be an property of the caldav object.

Any idea?

Kind regards
Jan