Sending e-mails during multiple bookings

all properties selected for booking at the same time

Are you asking if you were to book multiple things at the same time, try and send a single email that would say "you have booked the following three openings..." with data? That possibly could be tricky to disable transactional emails and put them in a queue for maybe 15 minutes then send a summary email, maybe you could do something with ECA → ? Also I can probably implement this as described later.

The only thing missing for complete happiness would be that the owner of each booked service would also receive an e-mail with information about what was additionally booked.

So the owner of each booked service would mean the admin side, the person who is getting notifications that someone else booked something? With that, you're wanting an email that would go out the day before or something to the admin with a list of everyone who has booked for the full day or something like that?

For both of those use cases let me know if I described what you want, if not try to detail exactly what you want, so I can look into getting that setup.

Notification Overhaul
I have started a pretty large overhaul of the notifications on the module and handling that under this issue: https://www.drupal.org/project/bookable_calendar/issues/3309578 ✨ Add ability to send reminder emails to Booking Contacts X time before Opening Instance starts. Fixed

My current vision for the overhaul is inspired by Webform notifications, where it's a separate entity you make with settings on it that then run based on a cron. I originally was thinking it would just be time related, to send X hours before set opening or X hours after. I could expand that to also allow sending an email every day at 8am with a summary for the day, and possibly other things if that would solve your issues.

Hi. thanks for the answer. It was more like this case:

I offer two services. The surfer has the option to book either one or the other or both.

If he indicates that he wants to book both services, then instead of sending him two e-mails, it would be nice if he got one confirmation message instead of two. This message should contain information about which instances he has reserved. It would be good if the information about reserved instances was specified as a token, then it could be used in several confirmation messages.

By the way, in the view where we use vbo, could you add information about the reserved instance instead of the reserved calendar? It happens that I have to have several instances within one calendar.