The settings are listed in the example
conf.d/15-lda.conf file. The important settings are:
postmaster_addressis used as the From: header address in bounce mails
hostnameis used in generated Message-IDs and in Reporting-UA: header in bounce mails
sendmail_pathis used to send mails. Note that the default is /usr/sbin/sendmail, which doesn’t necessarily work the same as
Alternatively you can use submission_host to send mails via the specified SMTP server.
auth_socket_pathspecifies the UNIX socket to auth-userdb where LDA can lookup userdb information when -d parameter is used. See below how to configure Dovecot to configure the socket.
The config files must be world readable to enable dovecot-lda process read them, while running with user privileges. You can put password related settings to a separate file, which you include with
!include_try and dovecot-lda skips them.