When using BulletedList() in a notification to enhance the readability of the notifications, it doet not work. Though the initial preview shows what I want. See below.
However when the notifcations (around 03.00 AM) runs and delivers the message via email, it became one line of text. See below:
Notifications suffer quite a bit from unexpected behaviour and various error messages. Since this one stood out, I took the time to report it.
I will solve the issue following the suggestion of @joost_mineur 
Character(13) + Character(10)
The public link to this doc is : Happy Birthday
best, Christiaan