And...I'll answer to myself as it finally works
Everything required is here :
viewtopic.php?f=31&t=24618
1) the email add-on must be installed and working
2) in the TCL tab in the MailAddon the first line must be "set serviceliste [encoding convertfrom utf-8 [lindex $argv 1]]" without quotation marks
3) in mail template no. of your choice "$serviceliste" must be entered without quotation marks in the mail text field (what else is there is not interesting)
Use TCL must be ticked
4) the CUxD add-on must be installed :
viewtopic.php?f=37&t=15298
4b) REBOOT the CCU
5) configuring CUxD was a bit unclear to me...what I did from the add-on "set" configuration page of CUxD
- go the last page "Geräte"
- From "CUxD Gerätetyp:", select "(28) System"
- Funktion: "Exec"
- and then "Gerät auf CCU erzeugen"
6) Go back to CCU GUI and go to "Teach-In Devices". You'll find an incoming message in the "inbox". Go to it and validate it.
6b) for security....I did REBOOT again
7) In the script provided on the page (first line of this post) I ensured that:
- var USE_MAIL = "yes";
- var MAIL_ID = "03"; This my my choice ! I prepared the email "03" for this purpose
var MAIL_CUXD_ID = "CUX2801001:1"; must match the created CUxD "System"
Of course you must create a program on the CCU that will, for example:
- condition if: system state, more or equal to 0, trigger when updated
- activity: script -> delayed by 1 sec
Again a huge thanks to alchie who wrote this procedure !