I'm going to be upgrading our 70 user NE from 5.0.2 to 5.0.4 this evening. When I make the full backup before the upgrade, should I place the server into Maintenance mode to prevent any new mail from being delivered that won't be included in the backup?

Should I also copy that full backup (and the redo logs) to another machine?

I'm worried about, in the event of catastrophe, losing mails received after this last full backup.