Solved

Multiple domains having email sent by the same server

Posted on 2009-07-02
4
292 Views
Last Modified: 2012-05-07
Here's the scenario:  We own four different companies and have four independent domains with the email server for each domain hosted on the same machine (same physical machine, same physical software, same static ip address).  In the past, we've had issues with email sent from this server being blocked because of no reverse DNS on the domains so we had that set up a few years ago.  For the most part, this works fine, but we still run into a few servers rejecting our email.

Since all four domains have a reverse DNS pointing to the same IP address, when you do a reverse DNS on the IP address, you will have a different one of the four domains returned as the hosting domain each time.  By this I mean on the first reverse DNS lookup, you will be told that domain #1 is the hosting domain.  On the second reverse DNS lookup, you will be told that domain #2 is the hosting domain and so on for the 3rd and 4th lookup.  On the 5th lookup, it rolls back to listing domain #1 as the hosting domain and repeats the whole thing in the same order.  By doing this, I would think that you actually only have a 25% chance of the domain that the email is being sent from actually being the domain that is returned when the receiving email server does a reverse DNS to check to see if it's spam.

My questions are:
1. How should I set things up in this situation so that the reverse DNS functions properly?
2. We're using Microsoft Echange Server as our email server so could we do something like assign more static ip addresses to our DSL connection and then use those other ip addresses with new virtual SMTP servers in Exchange?  If so, how would that work with only one NIC installed in the server?
3. How would you tell Exchange Server which ip address to use to send the email for each domain?

Thank You in advance for any help available on this issue.
0
Comment
Question by:crosstec
  • 2
  • 2
4 Comments
 
LVL 26

Accepted Solution

by:
jar3817 earned 500 total points
Comment Utility
You just need 1 PTR record. It doesn't matter what it is, as long as it is descriptive and non-generic (mail.oneofyourdomains.com). The reverse dns doesn't have to match the FROM domain on the email, so you don't need to worry about the other 3 domains, just use whatever the main domain is.
0
 

Author Comment

by:crosstec
Comment Utility
I received a new email about a message that was blocked today.  In the response message, it says "Client host [mail.servername.com] blocked by zen.spamhaus.org; http://www.spamhaus.org/query/bl?ip=<insert ip address here>"  The internal static ip address for one of our servers that sends shipment confirmation emails was in the <insert ip address here> spot.  Of course, the internal ip address is different than our external ip address, but how is this internal ip address being sent along with an outgoing email?  Shouldn't the internet only be able to see our external static ip address?  When following the link in the email, it states that the ip address range has been identified by Spamhaus as not meeting their policy for IPs which should deliver 'direct-to-mx' mail to PBL users.  That's completely understandable, as this ip address shouldn't be seen in the first place.  Spamhaus should only be seeing our public ip address, right?  How do we fix this?
0
 
LVL 26

Expert Comment

by:jar3817
Comment Utility
Does this server that sends the shipment confirmations relay all outgoing mail to your main mail server? Perhaps that is the server that checks spamhaus? That's the only way I can think of for the internal IP to be checked.
0
 

Author Comment

by:crosstec
Comment Utility
The server that sends the shipment confirmations does relay the mail through the main mail server.  It doesn't contact spamhaus in any way, though.  It's just an internal server that uses the Exchange Server on our main server to send these emails.
0

Featured Post

Highfive + Dolby Voice = No More Audio Complaints!

Poor audio quality is one of the top reasons people don’t use video conferencing. Get the crispest, clearest audio powered by Dolby Voice in every meeting. Highfive and Dolby Voice deliver the best video conferencing and audio experience for every meeting and every room.

Join & Write a Comment

ADCs have gained traction within the last decade, largely due to increased demand for legacy load balancing appliances to handle more advanced application delivery requirements and improve application performance.
Local Continuous Replication is a cost effective and quick way of backing up Exchange server data. The following article describes the steps required to configure Local Continuous Replication. Also, the article tells you how to restore from a backup…
In this video we show how to create an email address policy 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 Mail Flow…
The purpose of this video is to demonstrate how to set up a Mailchimp campaign. This will include styling and adding elements to a newsletter/email. This will be demonstrated using a Windows 8 PC. Mailchimp will be used. Log into your Mailchim…

772 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

Need Help in Real-Time?

Connect with top rated Experts

12 Experts available now in Live!

Get 1:1 Help Now