[Mailman-Users] Users with utf-8

I try to add member to maillist.

./add_members -r filename.txt listname

in the file filename.txt it will exist a user like Lönn <lonn@gmail.com> # Written as utf-8

When I look at memberlist afterwards at the web will it look like

lonn@gmail.com Lönn # Written the utf-8 as two characters

What is the problem and what is the solution

/LeSve