Simple Slackware Sendmail Server

Hi folks!!

I almost can’t believe how long it’s been since I last posted anything on here! I’ve learnt loads, so undoubtedly I’ll be making a few new posts in the near future! Anyway, on with the post…

Setting up Sendmail in a full install of Slackware 12+ (I’ve not tried it in any previous versions) is as easy as 123… Just su to root, and enter the following…
cd /usr/share/sendmail/cf/cf
sh Build sendmail-slackware.mc
cp sendmail-slackware.cf /etc/mail/sendmail.cf
cp submit.cf /etc/mail/
chmod +x /etc/rc.d/rc.sendmail
/etc/rc.d/rc.sendmail start

That’s it configured (in a very simple manner) and started. That wasn’t what caused me all the trouble. The pain in my neck was caused when I tried to use telnet to test the server. I typed the following…
telnet localhost 25
HELO identifymyself
MAIL FROM: myaddress@mylittleemailserver.com

For the first two commands, I got the correct response. 220 on login, then 250 after the HELO.

After the MAIL FROM command, however, I got the response “550 5.0.0. Access Denied”. After much delving into the guts of the system, and making sure that my firewall wasn’t blocking anything from 127.0.0.1, I discovered the root of the problem. I had used the hosts.allow file fairly extensively to block external and internal access to services, and I had not included sendmail into this. The simple fix to the problem was to add the following to the /etc/hosts.allow and restart the sendmail server.
sendmail : ALL@127.0.0. ALL@10.0.0. ALL@192.168.1.

Now the use of telnet to send a test email goes smoothly, as follows (server responses are in parentheses):
telnet localhost 25
(220 myserver.mydomain ESMTP Sendmail 8.14.2/8.14.2)
HELO identifymyself
(250 myserver.mydomain Hello localhost [127.0.0.1], pleased to meet you)
MAIL FROM: randomaddress@randomdomain.com
(250 2.1.0 randomaddress@randomdomain.com... Sender ok)
RCPT TO: my.email.address@my.own.domain.com
(250 2.1.5 my.email.address@my.own.domain.com... Recipient ok)
DATA
(354 Enter mail, end with "." on a line by itself)
Test Email. Just for testing purposes.
.
(250 2.0.0 0094t89gfdgd09 Message accepted for delivery)
^]
quit

I then checked my email account and found a subject-less email with the sender “randomaddress@randomdomain.com”, and the text “Test Email. Just for testing purposes.”

Fantastic!!

n00b

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