Solved

Exchange 2003 blacklisted

Posted on 2006-11-28
7
394 Views
Last Modified: 2010-03-06
I am new to exchange 2003, Since we have made the cut to it I have been blacklisted about every 3 days or so. I need help in trying to track down the problem. I have tested for open relays and have found none. when i was using exchange 2000 I never had any issues. Please Help!!!!

Thanks
Chad Logan
Network Administrator
Tiffin Motorhomes Inc.
0
Comment
Question by:tiffinIT
  • 2
  • 2
  • 2
  • +1
7 Comments
 
LVL 104

Expert Comment

by:Sembee
ID: 18027991
What is the reason for blacklisting? They will usually tell you.

Has the server been secured?
Do you have lots of messages in your queues?
Are you trying to send NDRs for non-valid users?

Simon.
0
 

Author Comment

by:tiffinIT
ID: 18028177
I am recieving bounce messages that give me the listing site, but I went to the mx toolbox site and did a quey and it displayed anll of the listing sites that i have been listed on. We do not do mass mailing or anything of that nature. Can you elaborate more on securing the server. I am checking the queues now to see how the message loads look. I am not sending Ndr's .  Is it possilbe that it is not coming from my servers? Maybe spoofing or someone internally has spyware that is sending out of that external ip
0
 
LVL 104

Accepted Solution

by:
Sembee earned 500 total points
ID: 18028682
If you only have a single IP address and are sharing it, then there is always the possibility that you have a compromised machine on your network. Quickest way to spot that is to block port 25 for all traffic except the Exchange server and see what is logged in the firewall. A compromised machine will quick show up.

Exchange is relay secure by default, but there are other attacks that can be made on Exchange.
The main two are NDR attacks and authenticated user.

NDR attacks is where email is sent to your server with non-valid users on purpose. The server then bounces the email back to the "sender" which is spoofed and is the real target. Enabling the recipient filter and tar pit deals with those.

Authenticated user is where relaying is allowed in Exchange if a valid username and password is used. The usual target is the administrator account. You can change the default settings of Exchange so that authenticated users cannot relay, or a small subset are able to.

http://www.amset.info/exchange/smtp-relaysecure.asp
http://www.amset.info/exchange/filter-unknown.asp

Simon.
0
PRTG Network Monitor: Intuitive Network Monitoring

Network Monitoring is essential to ensure that computer systems and network devices are running. Use PRTG to monitor LANs, servers, websites, applications and devices, bandwidth, virtual environments, remote systems, IoT, and many more. PRTG is easy to set up & use.

 

Expert Comment

by:ndbuster
ID: 18029459
I've been thru a similar problem. We changed the Global Public address for port 25 on the firewall to a different address. Once that was changed, the black lists do not have that address and you are no longer black listed. However you may get blacklisted again...so locking down port 25 so that only 1 or 2 exchange bridgehead servers can send outbound email is a great idea.

This prevents any potentially infected machines with SMTP engines from sending email. Also be sure that SMTP is set to send mail for only "authenticated" users. If you already checked for an open relay that is good becuase you don't want an open relay internally or especially externally.

If you do need to relay internally, then add the IP addresses of those machines that cannot authenticate and need to relay to the SMTP virtual server.
0
 
LVL 23

Expert Comment

by:Stacy Spear
ID: 18030229
I would also lock down 587. Some bots use that because most network guys worth half their weight in salt know to check 25 and to lock it.

I would also add a SPF to your DNS record. So that anyone doing RDNS can see that what is your authorized sending server. MS got a wizard here for doing so http://www.microsoft.com/mscorp/safety/content/technologies/senderid/wizard/default.aspx
0
 

Author Comment

by:tiffinIT
ID: 18030596
i have locked down port 25 a long time ago i will try to lock down port 587. I went into the pix and did a show port on port 25 and found 2 internal ips flooding it with traffic. SO i am going to look at those machines first and see if that is the cause of my problems.
0
 
LVL 23

Expert Comment

by:Stacy Spear
ID: 18030804
SPF won't help in this case, since all traffic is coming from the pix. Still good to have it.
0

Featured Post

Best Practices: Disaster Recovery Testing

Besides backup, any IT division should have a disaster recovery plan. You will find a few tips below relating to the development of such a plan and to what issues one should pay special attention in the course of backup planning.

Question has a verified solution.

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

We are happy to announce a brand new addition to our line of acclaimed email signature management products – CodeTwo Email Signatures for Office 365.
Scam emails are a huge burden for many businesses. Spotting one is not always easy. Follow our tips to identify if an email you receive is a scam.
To add imagery to an HTML email signature, you have two options available to you. You can either add a logo/image by embedding it directly into the signature or hosting it externally and linking to it. The vast majority of email clients display l…
This video demonstrates how to sync Microsoft Exchange Public Folders with smartphones using CodeTwo Exchange Sync and Exchange ActiveSync. To learn more about CodeTwo Exchange Sync and download the free trial, go to: http://www.codetwo.com/excha…

831 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