DNS Entries for Exchange and Comcast issues

[woodlandsprep]

Server: win 2003
Exchange 2003
Barracuda 300 Spam Filter port 25 forwarded to

I'm having an issue emailing to comcast.net email addresses, after a little research i see comcast mail servers, do reverse lookups, and i not for sure i have all the correct dns entries, for the mail server, i do have a A record, i tried to research on how to put in a PTR record, so when setting this up, i used the interal IP ( was that correct?) also I do not see a MX record in local DNS, do i need this? The mail was hosted offsite at first and we brought the mail onsite now, the company that registered the domain name, did put the MX record from their end.

Any help would be very appreciated!

 

[NJForensics]

Woodlandsprep-

I am not privy to all the details of your network... but based on the hardware you listed ... the following setup should be in place.

1. MX record for mail.yourdomain.com should point to your external IP address (or the NAT'd address if you have a block of IP's and are doing it that way)
2. A (also known as a PTR) from mail.yourdomain.com --> xx.xx.xx.xx (your external IP)
3. Call your ISP... get a reverse DNS entry created for the ip you are sending mail from (once again.. if you have a single external IP address then it would be this address)

These are some basic steps... if you would like to post the NDR's (Non-Delivery Report) you are receiving from Comcast.. then maybe i can be of a little more assistance.

Chris Clancy, EnCE,CCE

http://www.milestechnologies.com

" ... when you can't figure out what the problem is, find out what it isn't.... "

 

[1911man]

Chris covered it. We had the same issue with Comast when we went from Lotus Notes to Exchange. #3 (ISP add reverse DNS) was the final fix for us.

 

[woodlandsprep]

thanks again guys, i called SBC and had them setup the reverse DNS, hopefully this will stop all the delayed delivery emails we were getting.