Althought the idea is good, this is not a solution for us.
Cause, to do that, we need to duplicate 2 newsletters for each days we need to send the newsletter.
And, every day the newsletter is sent, the last send would not check if the last articles have being already sent yestarday, cause this is not the same newsletter each day.
I suppose, there is no other solution for the moment.
I hope, one day, this option would be developped ??