Restoring email from Time Machine

Help!! I am restoring my boss's iMac after a hard drive crash. Got everything back via Time Machine, with the exception of 90,000 emails. I have been searching online for a solution - I start Mail then Time Machine, the mail is displayed, with the instructions to click restore to restore the selected mailboxes, but the Restore button in Time Machine seems to be permanently disabled.

Thanks in advance for guidance here!

Your approach is the right one ..... have done it a couple of times myself and it works.

Once you restored mail from Time Machine you will see a folder on the left window pane in Mail that says " Time Machine " with a subfolder called " Recovered Messages ".
Your recovered mails will be in here.

When you enter Time Machine and select the date to restore from, give Time Machine some time to correctly locate the mails you want. I found that it sometimes takes a minute for the " Restore " button to become active.
( I am doing this wireless, hence the delay ..... I guess )

Cheers ... McBie

Thanks for your reply. After my initial post, we manually copied all the mailboxes from Time Machine and put them in the users/library/mail... directory (path was correct, my memory is poor). Also copied the Mail.Accounts.plist from Time Machine to Mac Hard Drive/Library/Mail/Account Types/com.apple../

Now, all new mail is accessible through the Mail app, but everything we copied, although in the mailbox, cannot be seen...?