Acknowledgement for external meetings are not sent by email

Hi there,

I use a nextcloud instance for my calender. The nextcloud calendar is configured correctly within my thunderbird/lightning.

If I get an invitation by email from a non-nextcloud user, I am able to “accept” the invitation and the meeting is shown in my calendar. Everything is fine, but…

…the external user doesn’t get any feedback/email about my acknowledgement of the invitation. Who is responsible for sending the acknoledgement? Nextcloud or Thunderbird/Lightning? Are there any ways to inform the organizer of the meeting about my acceptance?

Surely, I am able to check “prefer client side email scheduling”, but then meetings with nextcloud users of my own instance will be complicated…

Is there any way, nextcloud will send acknoledgements for external organizers by eMail?