Celebrate National IT Professionals Day with 3 months of free Premium Membership. Use Code ITDAY17

x
?
Solved

Spam Relay Problems

Posted on 2009-05-05
7
Medium Priority
?
375 Views
Last Modified: 2012-05-06
I hope someone can shed some light onto thiw. None of the solutions I have found have worked.

A customer has an SBS 2003 server running exchange. They use SMTP for both incoming and outgoing mail.

Someone is sending 1000's of mails through their server as postmaster@theirdomain.com

I have tried all sorts to block them but they appear to have random IP addresses. If I disable SMTP relay then nobody can send or recieve mails. If I turn on authentication then outside servers cannot send mail to their mail server.

Hope someone has come across this before.

Thanks in advance
0
Comment
Question by:jgearhart
[X]
Welcome to Experts Exchange

Add your voice to the tech community where 5M+ people just like you are talking about what matters.

  • Help others & share knowledge
  • Earn cash & points
  • Learn & ask questions
  • 3
  • 2
  • 2
7 Comments
 
LVL 24

Accepted Solution

by:
Rajith Enchiparambil earned 1200 total points
ID: 24304189
This is NDR attack. Configure recipient filtering, smtp tarpitting.

Follow this article in full http://www.amset.info/exchange/spam-cleanup.asp

http://enchiparambil.com/smtp_tarpitting_for_exchange.aspx

Rajith.
0
 
LVL 24

Assisted Solution

by:Rajith Enchiparambil
Rajith Enchiparambil earned 1200 total points
ID: 24304194
0
 
LVL 11

Assisted Solution

by:g000se
g000se earned 800 total points
ID: 24304219
Helllo,

In Exchange look under- Message Delivery.  You can block the Spam
0
Industry Leaders: We Want Your Opinion!

We value your feedback.

Take our survey and automatically be enter to win anyone of the following:
Yeti Cooler, Amazon eGift Card, and Movie eGift Card!

 

Author Comment

by:jgearhart
ID: 24304684
I have checked using telnet and according to that the system is secure. I am at a loss to explain how they are managing to send mails through the server. They are sending them using out own postmaster address which I understand cannot be disabled.

The mail is going out FROM the server as postmaster not incoming as postmaster.

Is there a way to secure this so that only the system can recreate an outgoing mail as postmaster?

I have managed to stop the mails from leaving the server but they are just backing up in the queues now at a rate of about 600 per hour.

Any suggestions?

I have a watchguard x10e by the way if anyone has any suggestions on additional configuration options.
0
 
LVL 24

Assisted Solution

by:Rajith Enchiparambil
Rajith Enchiparambil earned 1200 total points
ID: 24305433
have you configured IMF in Exchange 2003, especially sender id filtering? What about smtp tarpitting?

Configure IMF as a measure to fight spam. In your case, it seems like the spammer is sending emails to non-existent users in your domain and your server is responding with an ndr when the user is not found.

http://www.petri.co.il/block_spam_with_exchange2003_imf.htm
0
 
LVL 11

Assisted Solution

by:g000se
g000se earned 800 total points
ID: 24305783
Using the message delivery in Exchange is a no cost solution in fighting against SPAM.  You can also block it at the client level too in Outlook.
0
 

Author Closing Comment

by:jgearhart
ID: 31577996
I managed to solve the problem using the watchguard SMTP proxy built into the router.

This seems to be the solution with the lowest resource overhead since the server is not particually powerful.

I basically told the router to reject all mails in both directions for postmaster@domain.com

This seems to have cured the problem.

Many Thanks for all your comments

I have split the points between you because nobody came up with a solution that solved the problems but you all pointed me in the correct direction.

0

Featured Post

Are your AD admin tools letting you down?

Managing Active Directory can get complicated.  Often, the native tools for managing AD are just not up to the task.  The largest Active Directory installations in the world have relied on one tool to manage their day-to-day administration tasks: Hyena. Start your trial today.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

In-place Upgrading Dirsync to Azure AD Connect
This article will help to fix the below errors for MS Exchange Server 2013 I. Certificate error "name on the security certificate is invalid or does not match the name of the site" II. Out of Office not working III. Make Internal URLs and Externa…
In this video we show how to create a mailbox database in Exchange 2013. We show this process by using the Exchange Admin Center. Log into Exchange Admin Center.: First we need to log into the Exchange Admin Center. Navigate to the Servers >> Data…
This video shows how to quickly and easily add an email signature for all users on Exchange 2016. The resulting signature is applied on a server level by Exchange Online. The email signature template has been downloaded from: www.mail-signatures…

730 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question