Related articles * [Dovecot](/index.php/Dovecot "Dovecot") * [Postfix](/index.php/Postfix "Postfix") * [Exim](/index.php/Exim "Exim") [OpenSMTPD](https://www.opensmtpd.org/) is a free SMTP server, developed as part of the OpenBSD project. ## Contents * [1 Installation](#Installation) * [2 Configuration](#Configuration) * [2.1 Local mail](#Local_mail) * [2.1.1 Local mail only](#Local_mail_only) * [2.1.2 Hybrid : local mail and relay](#Hybrid_:_local_mail_and_relay) * [2.1.3 Relay only](#Relay_only) * [2.2 Simple OpenSMTPD/mbox configuration](#Simple_OpenSMTPD.2Fmbox_configuration) * [2.2.1 TLS](#TLS) * [2.2.2 Create user accounts](#Create_user_accounts) * [2.2.3 Craft a simple smtpd.conf setup](#Craft_a_simple_smtpd.conf_setup) * [2.2.4 Create tables](#Create_tables) * [2.3 Test the configuration](#Test_the_configuration) * [3 Troubleshooting](#Troubleshooting) * [3.1 Console debugging](#Console_debugging) * [3.2 Subsystem tracing](#Subsystem_tracing) * [3.3 Manual Submission port authentication](#Manual_Submission_port_authentication) * [3.4 "Helo command rejected: need fully-qualified hostname"](#.22Helo_command_rejected:_need_fully-qualified_hostname.22) * [4 See also](#See_also) ## Installation [Install](/index.php/Install "Install") the [opensmtpd](https://www.archlinux.org/packages/?name=opensmtpd) package. ## Configuration OpenSMTPD is configured in `/etc/smtpd`. ### Local mail To have local mail working, for example for [cron](/index.php/Cron "Cron") mails, it is enough to simply [start](/index.php/Start "Start") `smtpd.service`. The default configuration of OpenSMTPD is to do local retrieval and delivery of mail, and also relay outgoing mail. See [smtpd.conf(5)](https://jlk.fjfi.cvut.cz/arch/manpages/man/smtpd.conf.5). #### Local mail only To do only local mail, the following is enough: `/etc/smtpd/smtpd.conf` ``` listen on localhost accept for local alias deliver to mbox ``` #### Hybrid : local mail and relay These two lines in `/etc/smtpd/smtpd.conf` : ``` accept for local alias deliver to mbox accept for any relay via "smtp://smtp.foo.bar" as "@foo.bar" ``` configure OpenSMTPD to : * send local email *locally*, without going through a relay (useful for cron & at mail notifications) * use a relay to send a mail outside of localhost Simply replace *smtp.foo.bar* by your ISP mail server, or another server at your convenience. #### Relay only To send all local emails through a relay invoke [procmail](/index.php/Procmail "Procmail"): `/etc/smtpd/smtpd.conf` ``` accept from local for local virtual deliver to mda "procmail -f -" accept from local for any relay via smtps+auth://label@smtp.foo.bar:465 auth as "foo@bar" ``` The aliases option is used for the local user mapping, for a simplified mapping you can use virtual aliases with a catch all: `/etc/smtpd/aliases` ``` @ foo@bar ``` ### Simple OpenSMTPD/mbox configuration #### TLS To obtain a certificate, see [OpenSSL#Certificates](/index.php/OpenSSL#Certificates "OpenSSL"). **Note:** OpenSMTPD has solid defaults, SSLv3 is always disabled and the default `ciphers` are not known to be insecure. You might still want to test the server as described in [Server-side TLS](/index.php/Server-side_TLS "Server-side TLS"). #### Create user accounts * Create a user account on the mail server for each desired mailbox. ``` # useradd -m -s /bin/bash roger # useradd -m -s /bin/bash shirley ``` * OpenSMTPD will deliver messages to the user account's mbox file at `/var/spool/mail/**` * Multiple SMTP email addresses can be routed to a given mbox if desired. #### Craft a simple smtpd.conf setup * A working configuration can be had in as little as nine lines! `/etc/smtpd/smtpd.conf` ``` pki mx.domain.tld certificate "/etc/smtpd/tls/smtpd.crt" pki mx.domain.tld key "/etc/smtpd/tls/smtpd.key" table creds "/etc/smtpd/creds" table vdoms "/etc/smtpd/vdoms" table vusers "/etc/smtpd/vusers" listen on eth0 tls pki mx.domain.tld listen on eth0 port 587 tls-require pki mx.domain.tld auth accept from any for domain virtual deliver to mbox accept for any relay ``` #### Create tables * For the domain table file; simply put one domain per line `/etc/smtpd/vdoms` ``` personaldomain.org businessname.com ``` * For the user table file; list one inbound SMTP email address per line and then map it to an mbox user account name, SMTP email address, or any combination of the two on the right, separated by commas. `/etc/smtpd/vusers` ``` roger@personaldomain.org roger newsletters@personaldomain.org roger,roger.rulz@gmail.com roger@businessname.com roger shirley@businessname.com shirley info@businessname.com roger,shirley contact@businessname.com info@businessname.com ``` * For the creds table file; put the user name in the 1st column and the password hash in the 2nd column `/etc/smtpd/creds` ``` roger shirley ``` ### Test the configuration ``` # smtpd -n ``` If you get a message that says 'configuration OK' - you're ready to [rock and roll](/index.php/Systemd "Systemd"). If not, work on any configuration errors and try again. ## Troubleshooting ### Console debugging If you're having problems with mail delivery, try [stopping](/index.php/Stop "Stop") the `smtpd.service` and launching the daemon manually with the 'do not daemonize' and 'verbose output' options. Then watch the console for errors. ``` # smtpd -dv ``` ### Subsystem tracing Add the `-T` flag to get real-time subsystem tracing ``` # smtpd -dv -T smtp ``` Alternately, use the `smtpctl trace **` command if the daemon is already running. The trace output will appear in the console output above as well as the journalctl output for the smtpd.service. For example: ``` # smtpctl trace expand && smtpctl trace lookup ``` ...will trace both aliases/virtual/forward expansion and user/credentials lookups ### Manual Submission port authentication * Encode username and password in base64 ``` # printf 'username\0username\0password' | base64 ``` * Connect to submission port using `openssl s_client` command ``` # openssl s_client -host mx.domain.tld -port 587 -starttls smtp ``` * enter `ehlo myhostname` followed by `AUTH PLAIN`. Paste in the base64 string from step above after `334` response. ``` 250 HELP ehlo test.domain.tld 250-mx.hostname.tld Hello test.domain.tld [5.5.5.5], pleased to meet you 250-8BITMIME 250-ENHANCEDSTATUSCODES 250-SIZE 36700160 250-DSN 250-AUTH PLAIN LOGIN 250 HELP AUTH PLAIN 334 dXNlcm5hbWUAdXNlcm5hbWUAcGFzc3dvcmQ= 235 2.0.0: Authentication succeeded ``` ### "Helo command rejected: need fully-qualified hostname" When sending email, if you get this kind of messages, set your FQDN in the file `/etc/smtpd/mailname`. Otherwise, the server name is derived from the local hostname returned by gethostname(3), either directly if it is a fully qualified domain name, or by retreiving the associated canonical name through getaddrinfo(3). ## See also * [Wikipedia:OpenSMTPD](https://en.wikipedia.org/wiki/OpenSMTPD "wikipedia:OpenSMTPD") * OpenSMTPD pairs well with [Dovecot](/index.php/Dovecot "Dovecot"). Combine the two for a nice minimalist mailserver * [OpenSMTPD project page](http://opensmtpd.org/) * [Simple SMTP server with OpenSMTPD](https://coderwall.com/p/eejzja)