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How to Reject Mail if Originator's Domain has no MX Record

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How to Reject Mail if Originator's Domain has no MX Record - 21.Oct.2002 12:29:00 AM   
ddavila

 

Posts: 1
Joined: 21.Oct.2002
From: San Jose
Status: offline
Ever get unsolicited email from non-existant domains? For example, porn@asdkjg.com?

You've tried pinging mail.asdkjg.com and you get no response?

Wouldn't it be nice if Exchange 2k had some feature where it does a reverse DNS lookup on the senders MX record and rejects the mail if a valid MX record doesn't exist? Seems simple enough. But, per MS article Q297412, this feature is not part of Exchange. This doesn't make sense. Especially, when MS article Q319356 appears to say that it is a part of Exchange.

Try this on your Exchange server...

telnet yourmailserverIP 25
helo
mail from:porn@asdkjg.com
rcpt to:yourownemailaccountonyourmailserver
data [hit enter]
[type a test message. Theoretically, this message should not get through because the senders domain does not exist. Try pinging asdkjg.com if you don't believe me. hit enter at the end of your message. then type a period. then hit enter. your message should be queued]
quit

Now, launch your email client. You will see a message from porn@asdkjg.com addressed to you. This is not a good thing. Does anyone know how to fix this security hole?
Post #: 1
RE: How to Reject Mail if Originator's Domain has no MX... - 1.Nov.2002 9:36:00 PM   
stmatte

 

Posts: 4
Joined: 1.Nov.2002
From: USA
Status: offline
As far as I know, you would need to get an anti spamming software for Exchange to accomplish this.

(in reply to ddavila)
Post #: 2
RE: How to Reject Mail if Originator's Domain has no MX... - 2.Nov.2002 5:25:00 AM   
msaleem

 

Posts: 12
Joined: 7.Aug.2002
From: Chicago
Status: offline
I have similar problem with my exchange server. I have install WEB Shield for SMTP.
WebShield SMTP is designed to scan SMTP mail for viruses and other malicious code. WebShield SMTP scans all inbound and outbound email traffic passing through the SMTP. Webshield enables you to block specific SPAM email entering your organization, saving your valuable network resources. It also prevents individuals from using your servers to host SPAM email, giving you greater control and security within your network. to the security you gain with WebShield SMTP, the management communication channel requires authentication with the server, preventing unauthorized machines from accessing WebShield.

(in reply to ddavila)
Post #: 3
RE: How to Reject Mail if Originator's Domain has no MX... - 14.Nov.2002 7:57:00 AM   
element6

 

Posts: 8
Joined: 14.Nov.2002
From: Los Angeles, CA
Status: offline
Yep. I think Microsoft left that out in purpose so that the small software developers can make money off of buying Add-on features.

Microsoft Exchange Server 2000 DOES NOT HAVE an ability to reject e-mails from invalid or unverified RDNS results. Don't know why they even have the feature built-in to the Virtual SMTP server....

My solution was to spend $300 & built a Linux based SMTP server for inbound traffic on port 25, and have set up a separate Port for OWA users on the Exchange & outbound traffic (because I did not want additional software running on the Exchange server to lower the performance.)

(in reply to ddavila)
Post #: 4

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