Switching from Eudora to Thunderbird

I've spent the last couple of days switching e-mail software from Eudora to Thunderbird. Apparently this takes quite some time. Though Thunderbird has an import function, I couldn't import all my e-mails from Eudora (Thunderbird had trouble reading more than 1000 of my e-mails). Furthermore it wasn't possible to import the exact folder structure, so I had to rebuild this manually. Allmost done with this I got really scared. Suddenly all my mails and folders i Thunderbird were gone. Fortunately I was able to solve this problem to. Finally I've experienced problems with sudden errors in Thunderbird followed by immidiate exit from the program.

Hopefully this is a one time "pleasure". Else I will be forced to switch e-mail software again.