Add your user to group upas:

; con /srv/fscons
prompt: uname upas +bootes

To break out of the console, type ^\ (ctrl+\) then q to quit

prompt: >>> 
	(b)reak, (q)uit, (i)nterrupt, toggle printing (r)eturns, (.)continue, (!cmd)
>>> q

Edit /mail/lib/smtpd.conf. In particular, you need to edit defaultdomain.

#
#	sample smtpd configuration options for inside connections
#

#
#	replace YOURDOM with the name of your domain
#	replace 10.0.0.0 with the IP address range of your networks

defaultdomain		YOURDOM.com
norelay			on	#allow relaying
verifysenderdom		off	#disable dns verification of sender domain
saveblockedmsg		on	#save blocked messages

#
# if norelay is on, you need to set the
# networks allowed to relay through 
# as well as the domains to accept mail for
#

ournets 192.168.0.0/16

#ourdomains *.fakedom.dom, *.fakedom.rog

Note: By default, /bin/service/tcp25 is set to executable. It must remain executable or the mail server won't be able to start

; cat /bin/service/tcp25
#!/bin/rc
#smtp serv net incalldir user

user=`{cat /dev/user}
exec upas/smtpd -f -r -s -n $3

If you have a certificate you have generated using acmed, you can enable StartTLS with -c:

exec upas/smtpd -c /sys/lib/tls/acmed/example.com.crt -f -r -s -n $3

Note: the -c argument currently has a bug where it does not send the full chain of the TLS certificate, so email clients that connect to it may report a certificate validation error.

Copy /mail/lib/rewrite.direct to /mail/lib/rewrite, while replacing YOURDOMAIN.DOM with your actual domain name.

You will also want to edit /mail/lib/names.local for the users you want to handle mail for.

Edit /mail/lib/remotemail to add the -C -s flags to turn on TLS encryption when sending. -C is needed in case some certificates don't validate properly:

#!/bin/rc
shift
sender=$1
shift
addr=$1
shift
fd=`{/bin/upas/aliasmail -f $sender}
switch($fd){
case *.*
	;
case *
	fd=yourdomain.dom
}
exec /bin/upas/smtp -s -h $fd $addr $sender $*

Make sure to replace yourdomain.dom with your actual domain name.

If you are logged in as a user other than the default hostowner (glenda), make sure to add the user to upas group:

; echo 'newuser $username +upas' >> /srv/fscons

Then create the user's mailbox:

; upas/nedmail -c

See dkim.ms guide for enabling dkim. Make sure to add spf and dmarc records as indicated in ndb.ms guide.

To test sending an email:

; upasname=sender@example.com upas/marshal -s 'Alpha Bravo Charlie' recipient@example.org

Type a message, then a newline, then EOF.

If your email address is simply $user, you may be able to omit the upasname variable provided the domain is correctly configured elsewhere.

To offer SMTP over TLS (submission port), we can no longer use /bin/service files, since by default, it starts the process as user none.

Instead, we will start upas/smtpd from cpustart, and call aux/listen with -t.

cpu% mkdir /cfg/$sysname/service.upas cpu% cp /bin/service/!tcp25 /cfg/$sysname/service.upas/tcp587

Then, we edit tcp587:

cpu% cat /cfg/$sysname/service.upas/tcp587 #!/bin/rc

user=`{cat /dev/user}

exec upas/smtpd -a -d -c /sys/lib/tls/acmed/example.com.crt -e -s -n $3

A line such as below must be added to /cfg/$sysname/cpustart to call service.upas:

auth/as upas aux/listen -p 128 -t /cfg/$sysname/service.upas

Warning: Calling auth/as may corrupt the namespace, and may require you later to call mntgen /mnt.

Make sure to set the file as executable:

cpu% chmod +x /cfg/$sysname/service.upas/tcp587

Last modified Sun Feb 22 23:52:28 PST 2026

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