postconf
Postfix configuration utility.
TLDR
Specify the directory of the main.cf configuration file instead of the default configuration directory
$ postconf -c [path/to/configuration_directory]
Edit the main.cf configuration file and update parameter settings with the "name=value" pairs
$ postconf -e
Print the default parameter settings of the main.cf instead of the actual settings
$ postconf -d
Display parameters only from the specified class. The class can be one of builtin, service, user or all
$ postconf -C [class]
List available SASL plug-in types for the Postfix SMTP server. The plug-in type is selected with the smtpd_sasl_type configuration parameter by specifying cyrus or dovecot as the name
$ postconf -a
List the names of all supported lookup table types. Lookup tables are specified as type:name in configuration files where the type can be btree, cdb, hash, mysql, etc
$ postconf -m