Mail Server Rejecting all Messages – Check your Blacklists relays.ordb.org is listing the WORLD



It’s unusual for mail servers to suddenly start rejecting messages internally and from external sources. That’s exactly what I saw though over the weekend. A mailserver running mdaemon on Windows 2000 was rejected ALMOST every message that was sent it’s way whether it was an internal mail sender and recipient or external sender to internal recipient. The really interesting things was to see a message sporadically succeed. This problem was with mdaemon, but could have occured with ANY mail server. Here’s why…


It sounds like the problem started March 27th around 5 AM or so, as I was told. I logged in remotely and manually attempted to send a message (telnet) and was immediately told invalid recipient after entering what I knew was a correct email address. I tried a second time and it accepted the recipient. Then, I tested further every further test failed. So, I researched mdaemon, I discovered that it has an adaptive spam filtering which can be enabled that essentially locks out a mail sender after receiving attempts to deliver to 3 non-existent addresses from that sender. (I was further informed that a system had been virus infected which made me suspicious that this could be what happened…)

Anyway, when I actually got to look at the server setup I saw the logging of mail transactions and started looking through. It looked as though there were two blacklists setup, relays.ordb.org and bl.spamcop.net

Hmmm… I’ve used blacklists before and was thinking I haven’t been using relays.ordb.org (the open relay database) lately. I wonder why… I can’t recall. So, I googled and discovered that the ordb was shutting down. But that was announced a year or so ago. Why would that start causing trouble now?

I continued my search and found…. from this site

3/26/08 Update: ORDB has “listed the entire world” — returning any query with a “listed” response. The result is that if you still have ORDB in your mail server config files, you’re now blocking 100% of your inbound mail. For anyone still trying to “use” ORDB, you’re not going to receive any inbound mail until you disable queries to it.

Ah! Disabled black list – restarted mail server – mail starts coming in. Now, I remember hurrying to remove it from all the mail servers that I administer when the news first came out. (This is a machine that someone else setup/configured and took care of.)

So, moral of the story to those using blacklists – it is good to stay informed of their current status. The occasional successful mail deliveries appeared to be caused by timeouts in looking up the sender in the database.

Related Posts

Blog Traffic Exchange Related Posts
  • Why? (Why couldn't AT&T make sure their mail servers weren't using old dialup IPs that are blacklisted....) Why do I always wind up being the one to discover problems? .... Today in checking mail I found a mail that had bounced back from one of my clients that uses bellsouth... Now bellsouth has recently been bought by AT&T and it appeared as though the mail had been......
  • Remote Tech Support with x11vnc and wrapper script So, the idea is that I wanted something "like" the Ultranvnc Single Click download, only for linux. The main idea being is that if someone is looking for a bit of desktop tech support on linux, we don't need to be giving instructions for 5 different package managers, or source......
  • Crossroads At this point, I doubt anyone is seeing this as the wordpress test install is not live to the public yet, but... I'm opening this one up for comments. On the old site, I had accumulated a bit of content along the lines of windows/linux tips, software recommendations and tech......
Blog Traffic Exchange Related Websites
  • Tech Support - Funny Video Series While surfing through Youtube, I stumbled across this fun-filled tech support video series. All of the videos are sure to give you good amount of chuckle. I liked all of them, but first one is my favorite. Surely a stress buster after a bad day in office :) Enjoy! Tech......
  • High Tech Deck Skate Park Choices There is a great deal of interest in high tech deck skate park materials today as more and more people are becoming interested in the sport once again. As you watch the interest in skateboarding becoming more popular every year, there is more reason than ever for the innovations in......
  • What You Need From a WordPress Hosting Company Wordpress has taken over the world of websites and blogs, creating a simple and easy way for individuals get information out into the world of the Internet. The system gives users an incredibly easy platform to create the blogs, information, and news sites that they need to be successful. The......
www.pdf24.org    Send article as PDF   

Similar Posts


See what happened this day in history from either BBC Wikipedia
Search:
Keywords:
Amazon Logo

Comments are closed.


Switch to our mobile site