I would go to the mail file on the workspace and then go to new copy. After creating the new copy locally it will create a new local replica ID. Then take the local copy and replace it with what is currently on the server.
I would not do as the above suggests, not because it won’t work though. To reduce file size using the compact command at the server you need to use 1 of 2 switches. Either you can use -B after the rest of the compact command, or a more efficient way is to use the -c command – BTW, the switches are case sensitive, that is an upper case b or a lower case c.
For example, run the following at the console
load compact mail\userfilename.nsf -c -i
This should compact and remove the white space.