SBS 2003 - Problem with delegating shared email permissions

G'day guys,

I have a new client who has a lovely outdated SBS 2003 server (I'm updating it in the next month).

Because I have just signed up to be there dedicated IT Support, they are now utilizing me to do some office migration.

As a result we have various users moving computers and email accounts changing to go to different people, or being phased out.

Now the issue for today is that they have a user account that started off as lets say Sam. Now Sam was replaced with Bob, who was replaced with Harry, who was replaced with Jeniffer and who finally has been replaced with a generic name called Production.

So now in Users and Groups under Admin Tools I have a display name of Sam but when I click on properties it says Production.

Now thats all fine and I don't really care, but the issue is that Production is being phased out. So a new user is taking over all the emails for production and needs to have all the calendar etc.

So this username, Kevin lets say, has the permissions apparently for Production. What I normally do is just give Kevin the mailbox rights for Production, when I open up properties for Production in Users and Groups and click on Advanced Exchange, then Mailbox rights.

So now I open Outlook with the user Kevin logged in and bring up the accounts details and add the mailbox Production. Click save and now outlook complains that it cannot expand the folder.

Obviously its a problem with permissions.

However I have done everything according to the Microsoft site and various other googling locations.

How can I force the permissions to take effect?
I've waited 24 hours and no change.

On any other newly created user account it works fine, permissions are applied within minutes and I'm off and racing. But this long term user account is completely munted and not playing ball.

Please help :)

Steve