Recovering deleted messages?

Hi all,

I've run postfix and dovecot for years, but they have been so trouble-free that I've never really learned in-depth how they work. :)

But now I have a user who accidentally used a POP client, and it deleted all his email. He told me this only days later, and it's now been days later still, and so of course he has sent and received email since. I have backups of course, but it is a feasible thing to 'merge' the deleted emails from the backup into his current mailboxes?

I couldn't find any FAQ for such a scenario, so thought I'd ask here...

Thanks,

Sean