How I configure dma for mail delivery in jails on my internet hosts

Aug 152022

This is based on a series of tweets which I now want to place into blog post. When I go searching for something I’ve done before, I usually check my blog first.

dma is “is a small Mail Transport Agent (MTA), designed for home and office use. It accepts mails from locally installed Mail User Agents (MUA) and delivers the mails either locally or to a remote destination. Remote delivery includes several features like TLS/SSL support and SMTP authentication.”

See the man page for more information.

I like it because configuration for my needs is similar and it comes with the base operating system.

In this blog post:

FreeBSD 13.1
It is assumed the jail will be relaying to a smarter host
In my case, the jails relay to the host itself. Only the host speaks to the outside mail servers.

/etc/dma/dma.conf

This is the /etc/dma/dma.conf I use:

SMARTHOST 127.163.0.25
SECURETRANSFER
STARTTLS

In my case, the jail host is configured to listen on 127.163.0.25.

/etc/mail/mailer.conf

I place this in /etc/mail/mailer.conf:

sendmail      /usr/libexec/dma
mailq         /usr/libexec/dma
newaliases    /usr/libexec/dma
rmail         /usr/libexec/dma

This tells the system to use dma, instead of say sendmail or postfix.

/usr/local/etc/cron.d/dma

I create a cronjob to retry requeued entries.

Here is what I put in /usr/local/etc/cron.d/dma:

*/30    *       *       *       *       root    /usr/libexec/dma -q

Disable any other mail clients

If you had another mail client in use, now is the time to disable and/or remove that.

Testing

This is the type of test I do:

root@r720-02-ingress01:/ # echo testing from ingress01 | mail dan@example.net
root@r720-02-ingress01:/ # tail /var/log/maillog
Aug 15 15:26:28 r720-02-ingress01 dma[91a57.800e48000][87172]:  trying delivery
Aug 15 15:26:28 r720-02-ingress01 dma[91a57.800e48000][87172]: using smarthost (127.163.0.25:25)
Aug 15 15:26:28 r720-02-ingress01 dma[91a57.800e48000][87172]: trying remote delivery to 127.163.0.25 [127.163.0.25] pref 0
Aug 15 15:26:28 r720-02-ingress01 dma[91a57.800e48000][87172]:  delivery successful
Aug 15 15:45:17 r720-02-ingress01 dma[91274][91092]: new mail from user=root uid=26 envelope_from=
Aug 15 15:45:17 r720-02-ingress01 dma[91274][91092]: mail to= queued as 91274.800e48000
Aug 15 15:45:17 r720-02-ingress01 dma[91274.800e48000][91093]:  trying delivery
Aug 15 15:45:17 r720-02-ingress01 dma[91274.800e48000][91093]: using smarthost (127.163.0.25:25)
Aug 15 15:45:17 r720-02-ingress01 dma[91274.800e48000][91093]: trying remote delivery to 127.163.0.25 [127.163.0.25] pref 0
Aug 15 15:45:17 r720-02-ingress01 dma[91274.800e48000][91093]:  delivery successful

The logs show the mail was delivered from this host to the jail’s host. From there it was delivered to my inbox.

Job done. Time for more beach.