POSTGRES_HOST
POSTGRES_USER
POSTGRES_PASSWORD
POSTGRES_DB

MAIL_DOMAIN
MAIL_HOSTNAME

DOVECOT_HOST
DOVECOT_SASL_PORT
DOVECOT_LMTP_PORT

POSTFIX_HOST

OPENDKIM_HOST
OPENDKIM_PORT

MILTER_SASL_HOST
MILTER_SASL_PORT

POSTSRS_HOST
POSTSRS_PORT_FORWARD
POSTSRS_PORT_REVERSE

EXIM_SMARTHOST_HOST
EXIM_SMARTHOST_USER
EXIM_SMARTHOST_PASSWORD