Something weird is happening.

[Krelian]

Here is the deal. We have some users complaining that some emails they are sending to their clients are bouncing back to them. I did a Nslookup for “MX” records for these domains and found out they don’t exist. Only an “A” record is available. I assume that must be the problem, but the users claims that other clients have no problem sending email to these folks. As a test, I sent a test email myself using my Yahoo account, and that email did go through. So, I can only conclude that somehow, on some email systems out there, they can resolve email domains using only a “A” record even when there is no “MX” record exist. Has anyone seen this before? If so, how can we configure our system so that the email servers can query the “A” record for email domain as well?

Thanks for the help.

Howard

 

[Frankenherder]

I suspect that your domain has been blacklisted as a spam location. Any e-mails you send to a location that subscribes to the black-listed site will be bounced. This is why Yahoo worked and not yours.

You may hav been listed for mail relaying or if you have a virus that started to do mass spamming in your network.

Matt

 

[egolds]

I think this may have happend on our e-mail server is there any way to find out if your server has been attacked in such a way that it is being used to send out spam?

 

[JettaWarrior]

You can check to see if your site is listed in a spam site database at

http://www.dnsstuff.com.

Joe

 

[egolds]

I found out our ip address was listed in 2 databases. I have removed them from the databases. We must have been used as an open relay.

To stop this I have added a Routing Restriction to only allow Hosts and clients with these IP addresses and listed our internal NAT addresses and mask.

Is that enough or is there more I should do?

Thanks for the help.