Question : How to extract mailbox for records.

I have a client that is closing up shop and they want to extract a mailbox totaling 8gb.

what is the best way for me to extract that mailbox and still allow the user to refer to it when he wants to find an email?

Answer : How to extract mailbox for records.

It really depens on what client you are using.

Could you check :
http://support.microsoft.com/kb/830336

And see if, in your situation, you have a bigger limit. If so, you can always export them. If not, you can try to create several archives, or export it to another format.