I've never used Laputa, so I can't speak to that, but I use Aldiko and have email books before.
When you email yourself the book it will end up in the downloads directory on your SD card. You need to move the file to \ebooks\import (by either using a file manager like Astro, or by connecting the phone to your computer and doing a drag and drop using MS Explorer). Once in the import directory open Aldiko them menu > import. Aldiko will then import all epub files in the Import directory and move them into the appropriate author directory - creating the directory if necessary.
If you're a Dropbox user, the process is a bit simpler. I have a 'phone' directory under my dropbox folder. Anything I want to send to my phone from my PC I put there. When you download epub files from dropbox on your phone, Aldiko 'intercepts' the file automatically moves it to the proper directory as though you had just done an 'import'. This is the method I use the most. I find it much easier to find and download books on my PC and Dropbox them to my phone, than any other method I've tried so far. (Yes, I know that Aldiko has links to some book sites that will automatically download into the correct place, but I've long since read all of those books that I'm interested in and have moved on to other sites)
BTW, I also use the dropbox method to download new ROMs to my phone. When I find one that's I want to try I download it on the PC and move it to the dropbox folder. Then when I'm ready to actually put it on my phone, which is often days later, I pull it from the dropbox.