trying now to solve a kmail puzzle

hi, everybody . . . after a little research, and spurred by that pile of stuff that wanted to be autoremoved, i went ahead last night and changed my sources.list to reflect Ubuntu-16.04-LTS and Preliminary Stable and did apt-get update and apt-get dist-upgrade. (ubuntu has traditionally supported LTS-to-LTS upgrades, which makes sense.) and so far, fingers crossed, everything is working. now comes the part that largely sparked all this upgrade frenzy (though the gemini project has figured in, too, this is now about my desktop machine): getting kmail to work with protonmail. i seem to have all the pieces installed. but there are some configuration issues that i cannot sort -- i simply don't know that much about the mechanics of email. i have the beta of the protonmail bridge, which is alleged to allow use of a local mail client in linux rather than being tied to protonmail's admittedly very nice webmail. the only configuration example they give, though, is thunderbird. might someone who knows mail well look through here and give me a sense of the analogs in kmail? most of it i can sort out, but such as the "IMAP exception" confounds me, as does where i'm supposed to tell kmail about 127.0.0.1:1143 and 127.0.0.1:1025. i know the numbers after the colons are the port, but no idea about the 127.0.0.1. there are a couple of other things that also puzzle me. the instructions, for thunderbird, are here: https://protonmail.com/bridge/thunderbird#1 that failing, does anyone know of a good way to export vast kmail message archives to thunderbird? dep Sent with [ProtonMail](https://protonmail.com/) Secure Email. Because privacy matters.