Postfix fatal: tipo de diccionario no compatible: mysql, fatal: no se puede ejecutar / usr / sbin / postconf

Estoy intentando ejecutar un servidor de correo, instalado postfix y dovecot, pero obtengo los siguientes errores al iniciar postfix.

Jan 22 20:09:19 ub18 postfix/postfix-script[10135]: starting the Postfix mail system
Jan 22 20:09:19 ub18 postfix/master[10137]: daemon started -- version 3.3.0, configuration /etc/postfix
Jan 22 20:09:59 ub18 postfix/postmap[10150]: fatal: unsupported dictionary type: mysql
Jan 22 20:10:06 ub18 postfix/postmap[10152]: fatal: unsupported dictionary type: mysql
Jan 22 20:19:54 ub18 postfix[10322]: Postfix is running with backwards-compatible default settings
Jan 22 20:19:54 ub18 postfix[10322]: See http://www.postfix.org/COMPATIBILITY_README.html for details
Jan 22 20:19:54 ub18 postfix[10322]: To disable backwards compatibility use "postconf compatibility_level=2" and "postfix reload"
Jan 22 20:19:55 ub18 postfix/postfix-script[10324]: fatal: cannot execute /usr/sbin/postconf!
Jan 22 20:19:56 ub18 postfix/master[10137]: terminating on signal 15
Jan 22 20:44:53 ub18 dovecot: master: Warning: Killed with signal 15 (by pid=10529 uid=0 code=kill)

salida postconf -m:

btree
cdb
cidr
environ
fail
hash
inline
internal
ldap
lmdb
memcache
mysql
nis
pcre
pgsql
pipemap
proxy
randmap
regexp
socketmap
sqlite
static
tcp
texthash
unionmap
unix

No tengo idea de qué hacer.