WISH: Add+Subtract Event Attendee email to/from Mass mailing (in the same project)

[JonBendtsen]

Feature Request

I wish that at the list of event Attendees I could select one or more event attendees and then do a mass action on the selection where the event attendees email would be added or subtracted from a mass mailing, because the current "Send by email" option is not a mass mailing and can only handle 25 people at the same time.

Given that mass mailings now have a project and event attendees comes from a project, I would like if the mass mailings of the same project was listed first. Then below that could be Open mass mailings:

1. without a project
2. other project

and it would be nice with some kind of visual divider between the different projects and mass mailings without a project.

Perhaps duplicate the same setup for the conference booth lists?

Use case

Making it easier to easily email different groups of attendees who have bought different kind of tickets. I use it for dance classes and events, and while I might need to send one message to EVERY participant, I might also need to send a message to all those in one particular class level + a different message to another class level.

Suggested implementation

No response

Suggested steps

No response

[JonBendtsen]

This other PR #37736 can partially fulfil what I wanted in this wish, but it is still not exactly the same.

[JonBendtsen]

When selecting the target mass mail I wish that it could somehow be done like when linking `Related Objects``

Actually, look at the 2 buttons below, you have link and cancel. In this wish, what if you had 3 buttons?

• Add preselected event attendees to selected mass mailings
• Subtract preselected event attendees from selected mass mailings
• Cancel

If done like this you don't need 2 lines in the popup mass action menu