Hmmm,
Well, I'm using SME7 and it doesn't. I pasted in your text and it failes
"This field cannot contain white-space"
I remove the white-space and try again:
"This field must contain only letters, numbers, dots, hypens and underscores and start with a letter"
So all you have left to take out is the comma and that's the delimiter. There is definately an email validation happening... It also doens't like the second @ symbol. Very deliberately designed to only allow you to forward to one user.
Really, I think this is moot. The ability to use groups and not have limits on the number of groups solves this just fine.