I've recently changed the way that I send mail using Wanderlust. I now connect to a remote SMTP server, which requires that I authenticate myself. Although Wanderlust supports this mode of operation, it prompts for the SMTP server's password. This is a pain as the password was never meant to be entered by a human, but saved into a file and quickly forgotten (easily done using, e.g., Exim). After reading code for a while, I finally found the secret: running elmo-passwd-alist-save will save all of your Wanderlust passwords to ~/.elmo/passwd. When Wanderlust first needs a password, it calls elmo-passwd-alist-load, which loads this file.