> Hmmmm....is ~vpopmail/etc/open-smtp a file I should have manually created at
> some point in time (touch open-smtp)?
No. As you use the MySQL backend, there is no need for that file. You
should have mentioned in your first post that you're using MySQL as a
Rule of thumb: If you did anything other besides a plain "./configure"
when compiling qmail, let us know your configure line if you post a
question, or tell us about ("I have compiled vpopmail with roaming users
support and the MySQL backend"); it prevents unneccessary confusion.
> Where I'm also
> lost, then, is that my /etc/tcp.smtp and /etc/tcp.smtp.cdb files are both
> owned by root:root at present (this seems incorrect to me) and are both
> chmod 644.
The tcp.smtp.cdb file has to writable to the user that handles the POP3
session for the authenticed user. In many cases, this is
vpopmail.vchkpw, but it might be another user if you created domains
with the "-u <user>" argument.
Try "chown vpopmail.vchkpw /etc/tcp.smtp.cdb" first and see if it works.