Activity Emails not sent

[NextClaus]

Maybe this will help you, if you are using “Group folders” app (instead of normal shares). Please check out my comment here:

Test mail works <> Mail notifications don't work

I think and hope I have found the issue: https://docs.nextcloud.com/server/latest/admin_manual/configuration_server/activity_configuration.html#activities-in-groupfolders-or-external-storages I will give it a try asap.