Postifx & Dovecot

There is not something specific, it's just the overall postfix/dovecot configuration.
I can read and understand an iptable's rule, and visualize what happens to the packet that matched the rule.
The same goes when i see an Apache stanza, even long view stanzas in BIND.

But when i see something like this:

# postconf -e "smtpd_sasl_type = dovecot"
# postconf -e "smtpd_sasl_auth_enable = yes"
# postconf -e "smtpd_recipient_restrictions = permit_mynetworks, permit_sasl_authenticated, reject_unauth_destination, reject"

I don't know.... I bought a book on Postfix and i will study it. Maybe i just have to become more familiar with the interconnects between Postfix-dovecot and the various authentication types.