User Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Firefox/78.0

Steps to reproduce:

Steps to reproduce:

1. Create an all-day multi-day calendar event w/ attendees. Notifications are sent and acceptance replies come in.
2. Move the event to another date.

Exact version is 78.0b4 (32-bit), on Windows.

Actual results:

No email notifications are sent to the attendees, about the modification.

Enabling verbose logging for the calendar shows the following error:

Lightning: cal.itip.checkAndSend: no response mode provided, falling back to USER mode.

1: [resource:///modules/calendar/utils/calItipUtils.jsm:818] checkAndSend
2: [resource:///modules/CalTransactionManager.jsm:100] onOperationComplete
3: [resource:///modules/calendar/utils/calProviderUtils.jsm:515] notifyPureOperationComplete
4: [resource:///modules/calendar/utils/calProviderUtils.jsm:534] notifyOperationComplete
5: [resource:///modules/CalStorageCalendar.jsm:495] doModifyItem
calItipUtils.jsm:815

Expected results:

The email notifications should have been sent to the attendees.

WFM at least on trunk.

Mihai, do you still see this?

Indeed, it seems to work with 80.0b5 (32-bit).

If you can confirm it works on 78.2, please close as WORKSFORME.

My beta-channel install is already upgraded to 81.0b1 (32-bit) now, so I can't confirm on the old version(s).

Let's mark this WFM. It's certainly working in general.