Senmail MTA open

[Anu Mathew]

Hi Alman,

Greetings. We too had an 8.8.6 Open relay, which appeared in almost all blacklists around the world. I would be more than happy in describing the steps that we adopted.

Have a look at http://www.sendmail.org/faq/section2.html#2.7 . It says "Some vendors have started shipping (or announced that they will soon ship) version 8 sendmail pre-configured for their machines. Unfortunately, in most cases this means you get a pre-compiled binary and a sendmail.cf file (that may need a bit of tweaking), but not much else of the "standard" version 8 sendmail installation kit. Silicon Graphics (SGI) and Hewlett-Packard are known to already be shipping version 8 sendmail in this fashion."

1) I would suggest to download and compile a recent and decent Sendmail version (www.sendmail.org). I run 8.11.4, and it has strongs rulesets to decline un-authorised relaying. Heard from mailing lists that 8.12.2 is a good deal too.
You can even lookup various RBLs (relay block lists) while handling a relay request.

2) Once you have a decent Sendmail running, you need to get your entry removed from the blacklists, which can be annoying. Otherwise, many MX hosts won't be accepting mails from you. Hit http://ordb.org and http://www.mail-abuse.org for more details, since theirs is perhaps the popular ORDB (open relay database) site. It may take a couple of days for your system to come clear from all the RBL.


Hope this helps,

Thanks

Anu Mathew

[alman]

Thanks Anu , I have sendmail 8.10 version , so I believe it should be ok .

Now I can't even send emails to certain domain , it says dns service unavailable.and domain not found

[Michael Elleby III_1]

Alman, are these specific domains that you were able to send to previously before you started having problems?

If not, then look at the newer sendmail.cf file, and insure that you have specified the correct relayhost that sendmail will send your mail to (DS macro). Also, check your mailertable (because even though he's there to help, with he incorrect info, he could make life difficult), and make sure you specify all domains, etc. that you want to send to with the smtp hosts handling the mail, and that they are included in this file.

For example:

yankee.com smtp:172.20.184.100
mikey.com smtp:172.20.184.100
blubird.com smtp:172.20.184.150

Here, the first two domains are being sent to he same smtp host to handle, and the third (blubird) is being sent to another host to handle. I usually use this function when I want two different hosts to handle certain mail destined for certain domains.
If I have

Once you have finished all of your modifications, stop and restart sendmail.

Your problem is a difficult one, because it was a challenge to review your original sendmail.cf file when it was so large and that is was the same file concatenated over and over again. But with a little re-configuration, you can get it working to something you can live with.

Mike-

[alman]

Mike, previously I was able to send emails to
everyone , but recently a few domains I couldn't send ,it started , when spamming happened. I cannot trace my domainname from US , but if trace from UK , our domain can be found. I suspect, because of spam , our domain might have been blocked somewhere. So far, I have used other tools to check whether my domains is blacklisted or not.But I found my domain was not been blacklisted.
Probably , some anti-spamming software 's ?????