dovecot security

[Rob Owens <rowens@ptd.net>]

I'm testing out dovecot-imapd and there are a couple things I can't figure
out.

1)  It seems like cleartext communication is disabled by default, and
only TLS or SSL is allowed.  I can't find this in the docs or conf file,
though.  Can anybody confirm this is the case?  

2)  There is a certificate used for secure communication w/ the server,
but I did not generate it myself.  Was it generated automatically for
me?  Or is it a default cert that I should replace with my own?

Thanks for any help.

-Rob