I have used 2 laptops over the last 2 years, and on each laptop I have set up my email accounts on them. I often had to go to each of the different laptops to retrieve specific e-mails, and as bad as it sounds I got used to it and it worked.
However, one of the laptops has now died (although I have a back up of the mailboxes on that laptop) and the other laptop I'm intending to give to my girlfriend for her to use. At the moment I have a desktop PC which I have rebuilt where I'm intending to put all of my emails on to it.
My problem is that I don't know how (or even if it's possible) to merge the different mailboxes from the different laptops and put them in to one mailbox which the desktop PC will use.
On the two laptops I used Thunderbird and on the Desktop PC I will also be using Thunderbird.