Did that already on Mon evening.

I imported my backup via mSDcard and all my accounts were there. Unfortunately i forgot that you have to install all Jollas app (mail, calender etc). So when i then went into the mail app all the server settings where empty.

Try it like this:
install mail, calendar and pretty anything from Jolla store you need and then run the backup. Maybe you are lucky and your emailsettings are there.