How to transfer kmail2 messages to Thunderbird?

[Paul]

Hi all,
I am fed up with kmail taking so long to do things and hogging the 
system.  I thought I would try Thunderbird, I installed it and set up 
accounts but I can not find my old mail which I need.
Where is kmail2 mail stored and can it be exported?
How can Thunderbird import the old messages?
Is Thunderbird a good choice or would another program be more suitable 
as a kmail replacement?

Why is everything so complicated, after all I just want to receive pop2 
email and save the history.

Please help a frustrated user.
Thanks
Paul
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