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About default relay of the sendmail

frank_14
Occasional Advisor

About default relay of the sendmail

I have a server(HP-UX) installed sendmail(8.9.3) as almost default value,I found that,if anyone set my server as smtp server,it always fowards the message without any authentication,it is so dangerous.
How should I set my sendmail.cf or others?Giving some docs or link sites to me is Ok too.

I appreciate your help!
5 REPLIES
Sridhar Bhaskarla
Honored Contributor

Re: About default relay of the sendmail

Frank,

The default sendmail.cf for sendmail version 8.9.x should deny relay. If not then you must be using the previous version of sendmail.cf. Try copying the new sendmail file in /usr/newconfig/etc/mail/sendmail.cf into /etc/mail/sendmail.cf and then restart sendmail and verify. It should work. The comment portion of your sendmail.cf file should display 8.9.

Once you copied this new sendmail.cf, your sendmail should deny relaying the mails. To verify -

$telnet your_system 25
...
helo your_system
...pleased to meet you
mail from:
250 ok
rcpt to:
550 relaying denied.
quit

...

But it is not default with 8.8 version of sendmail.

Good luck.

-Sri

You may be disappointed if you fail, but you are doomed if you don't try
frank_14
Occasional Advisor

Re: About default relay of the sendmail

yeah,you are right.My sendmail version is 8.9.3,but someone made a mistake for using the old .cf file of 8.7.x,I changed it and it works well now,thank you very much!
By the way,would you like to tell me which symbol in the config file control the relay fuction!
Sridhar Bhaskarla
Honored Contributor

Re: About default relay of the sendmail

Frank,

It's all in the RCPT TO: verification Ruleset. Check the lines under the comment "check_rcpt -- check SMTP "RCPT TO" " till

# anything else is
bogus
R$* $#error $@ 5.7.1 $: "550 Relaying denied"


-Sri
You may be disappointed if you fail, but you are doomed if you don't try
Tech Support_1
Occasional Advisor

Re: About default relay of the sendmail

Sendmail is very complicated, you could use a simpler and faster mail server like qmail: http://www.qmail.org.
If you are brave, and like sendmail you should get Sendmail; by Bran Costales and Eric Allman published by O'Reilly.
Apathy is ..................
frank_14
Occasional Advisor

Re: About default relay of the sendmail

Ok,I like to try the qmail.
thanks the eager Mr. Sridhar and Tech-support folk again.

frank