Calendar invite updates, attendance notifications and cancellations are (still) not working

[kkeijzer]

I run multiple Nextcloud servers, both private and for work. All my servers run Nextcloud 31.0.0 with Nextcloud Mail 4.2.3. I was very excited for #10116 to be merged as it promised to solve all issues regarding calendar invites, and basically all calendar-related bugs were closed by Nextcloud developers saying it would all be resolved by that PR.

Sadly, still not everything works.

Steps to reproduce

When I invite a user on my work server from my private server, an e-mail is sent.

Private server:

Work server:

When I click the Accept button, the event is added to the calendar of the test account on my work server.

On my private server, I get an e-mail saying the test account on my work server has accepted my invitation.

However, in my private calendar, I don't see a checkmark confirming the other party has accepted. It still says "Waiting for reply".

When I then change the time of the event by dragging the appointment in my private calendar, an update mail is sent.

The state remains set to Accepted, and there is no way for me to re-accept (or decline) the event now the time has changed.

In the calendar on my work server, the event is also not moved to the new time slot, and remains marked as Accepted.

When I try to add the modified .ics attachment to my calendar, it throws the error Could not create event, even though nothing is written to nextcloud.log.

I have to manually delete the event from my calendar, after which the selection bar re-appears in the Mail app.

Only then the event is re-added to the new time slot in my calendar.

This does, however, cause a decline mail to be sent to my private server, followed by an acceptance mail.

And in my private calendar, the attendance is still not updated.

Probably the worst thing is that when I delete the event from my private calendar, the attendee is notified that the event was cancelled, but this does not show any option to delete the event from their calendar.

Trying to import the updated .ics attachment throws the same error as before, so I have to manually delete the event from the calendar through the Calendar app. This then sends a mail saying the invitation was declined, which makes little sense, as the event was already cancelled by the organizer.

Expected behavior

When Nextcloud Mail receives a message with an .ics attachment that changes an invitation in any way, it should update the calendar object accordingly.

This does work perfectly well when using Thunderbird and a Nextcloud calendar. When I receive a meeting invitation in Thunderbird, I can accept or reject the invitation in the purple bar.

This is then added to my private Nextcloud calendar in Thunderbird, which obviously also shows in the Calendar app.

When I change the event's time by dragging it in the calendar of the organizer (the test account on my work server), a mail is sent saying the time has changed. Thunderbird's purple bar then gives me an option to re-accept or decline the event.

When I re-accept it, it is properly moved in my private Nextcloud calendar.

When I delete the event from the test account on my work server, a cancellation mail is sent. Thunderbird then allows me to delete the event from my calendar. When I click that button, the event is removed from my private Nextcloud calendar.

When I invite the test user on my work server from my private server, and accept that invitation from Nextcloud Mail, the acceptance notification mail shows an option in the purple bar in Thunderbird to update the status of the event.

When I click that button, the attendance is updated properly in my private calendar.

Actual behavior

Nextcloud Mail does not show the attendance selection bar in many situations it actually should. It also has no way to update others' attendance status and no way to delete calendar events.

When an event is updated, it doesn't show any options to re-accept or decline the invitation, nor does it change anything in the calendar object. So the state of your calendar and that of the organizer will be completely out of sync.

The same thing happens when an event is cancelled. There is no way to remove it from your calendar other than finding it manually.

Also, when an attendance notification is sent, Nextcloud Mail doesn't do anything with that, and all external participants remain in the "Waiting for reply" state.

When I use Thunderbird for any of these actions, everything works fine, so the issue is not Nextcloud itself. The backend handles all of these events without any issue. It is the Mail app that does not integrate properly yet.

These problems don't only exist between two Nextcloud servers, but also between Nextcloud and Google Calendar. I have the exact same problems with Nextcloud Mail (and lack of problems with Thunderbird) when I get invites from Google users. Most likely invites from Microsoft users will suffer the same fate, although I rarely interact with those, so I haven't been able to test that.

Mail app version

4.2.3

Nextcloud version

31.0.0

Mailserver or service

Postfix + Dovecot (both private and work)

Operating system

Debian 12 (private) and Ubuntu 24.04 (work)

PHP engine version

PHP 8.2 (private) and PHP 8.3 (work)

Nextcloud memory caching

APCu

Web server

Nginx

Database

MariaDB

Additional info

No response

[kostasvg]

👍

[kkeijzer]

One other issue is that the Mail app only shows the option to accept or decline an invitation when it is sent to the primary e-mail address known by Nextcloud.

When I invite myself on my secondary e-mail address (which is an alias on the mail server, so it arrives in the same mailbox), I don't get any meeting options in the mail.

Even though the secondary e-mail address is defined in my Nextcloud user settings.

And also as an alias in the Mail app's account settings.

When I send an invite to my primary e-mail address, the bar with the options is shown.

With Thunderbird, this does work. When I accept the invitation sent to my secondary e-mail address and want to add it to the Nextcloud calendar, it asks me to which calendar I want to add it and with which e-mail address I want to send a reply.

Here it says that the e-mail address of the calendar I selected is not on the guest list, but it allows me to send the reply with the e-mail address that was invited.

The reply is then received from the correct e-mail address.

[midimarcus]

Hello all,
I can add as a detail and confirmation of what @kkeijzer reported, that basically happens with invitations sent or managed from major providers like Gmail, Hotmail and Proton.