This document describes the process of configuring the OpenSMTPD service as part of the server mail system. The mail system includes the following services: OpenSMTPD, DKIMproxy and Dovecot. But only OpenSMTPD will be considered here.

## Creation of additional service files

First, let's create additional service files for the server, which will contain users, a list of hosts, and so on. And also we will restrict access to them for other users of the system.

    doas touch /etc/mail/domains
    doas touch /etc/mail/vusers
    doas touch /etc/mail/hosts
    doas touch /etc/mail/passwd


    doas chmod 640 /etc/mail/domains
    doas chmod 640 /etc/mail/vusers
    doas chmod 640 /etc/mail/hosts
    doas chmod 640 /etc/mail/passwd
    doas chmod 640 /etc/mail/smtpd.conf


## Creating a configuration file

The next step is to replace the contents of the standard configuration file as here:

    pki example.com cert "/etc/ssl/example/example.pem"
    pki example.com key "/etc/ssl/example/private/example.key"
    smtp max-message-size 5M
    table aliases file:/etc/mail/aliases
    table domains file:/etc/mail/domains
    table hosts file:/etc/mail/hosts
    table vusers file:/etc/mail/vusers
    table passwd file:/etc/mail/passwd
    filter check_rdns phase connect match !rdns junk
    filter check_fcrdns phase connect match !fcrdns junk
    listen on lo0 mask-src
    listen on lo0 port 10028 tag DKIM mask-src
    listen on egress port 25 tls pki example.com mask-src filter { check_rdns check_fcrdns }
    listen on egress port 587 tls-require pki grape.ircnow.org auth <passwd> mask-src filter { check_rdns check_fcrdns }
    action "local_mail" mbox alias <aliases>
    action "relay_dkim" relay host smtp://127.0.0.1:10027
    action "relay" relay
    action "lmtp" lmtp "/var/dovecot/lmtp" rcpt-to virtual <vusers>
    match from local for rcpt-to regex "^root@|^abuse@|^security@" action "local_mail"
    match from local for domain <domains> action "lmtp"
    match tag DKIM for any action "relay"
    match from local for any action "relay_dkim"
    match from src <hosts> for any action "relay_dkim"
    match from auth for any action "relay_dkim"
    match from any for domain <domains> action "lmtp"


## Additional files

In the first step, we created additional files, now we need to fill them with data.

The domains file is used to receive mail. Therefore, it must contain a list of domains from which the server is an endpoint. In our case, this is so:

    example.com


The hosts file is used for relay operation. It contains a list of remote hosts for which you are allowed to relay mail without authorization. In our case, this is so:

    10.10.10.10


The vusers file is used to receive mail. It contains a list of mailboxes. This is an example:

    admin@example.com		mailman
    hostmaster@example.com		mailman
    ircnowguy@example.com		mailman


The passwd file contains a list of accounts for authorization. This is a possible option:

    ircnowguy@example.com:$2b$09$hD17XLkUb4doE3bjvn4v1uYVF3/tldQBKvDTcCbDta1a6NZNA1zue


## Service start

    doas rcctl stop smtpd
    doas rm -r /var/spool/smtpd
    doas rcctl -d start smtpd


    doas rcctl -d start smtpd
    doing _rc_parse_conf
    doing _rc_quirks
    smtpd_flags empty, using default ><
    doing rc_check
    smtpd
    doing rc_start
    doing _rc_wait start
    doing rc_check
    doing _rc_write_runfile
    (ok)