Off - bandwith limit

good morning,

I would like to know somebody uses some type of band manager for
access the pop3.

I have many customers that look for emails through adsl.
and several customers come to look for to 300K other to 600K and other to
1M.
then I am wanting to do with that always the person looks for emails no
passing of 400K, same if she comes to 1M.

a guaranteed band for each connection. because the link is very expensive
for
to be increasing every hour.