What setting are you trying to implement, and what isn't working?
It looks like some of the IMAP settings have not been completely migrated to support dovecot - possibly because dovecot includes enhanced security by default.
If you want to see "connection refused" when you telnet to port 143 from the LAN, this seems to work:
config setprop imap access localhost
signal-event email-update
You can add a setting to /etc/dovecot.conf for "disable_plaintext_auth = yes" using a db variable, but that may cause other problems:
config setprop imap AllowPlainText disabled
signal-event email-update
(You can un-do the mods shown above using the commands below)
#restore default for imap 'access'
config setprop imap access private
#
# restore default dovecot config for plain text auth
config delprop imap AllowPlainText
#
# activate changes
signal-event email-update
There's a setting in /etc/dovecot/conf.d/10-ssl.conf to require ssl, but that setting does not seem to be templated. Change it by editing the file directly and restarting dovecot:
sed -i s/\#ssl\ \=\ yes/ssl\ \=\ required/ /etc/dovecot/conf.d/10-ssl.conf
sv t dovecot
(Undo...)
sed -i s/ssl\ \=\ required/\#ssl\ \=\ yes/ /etc/dovecot/conf.d/10-ssl.conf
sv t dovecot