"network error during host resolution" for some domains

[tgentry61103]

I'm having a couple of possibly related problems. First, email to aol.com and yahoo.com domains gets stuck in the outbound queue with the "network error during host resolution" message. I can do nslookup and ping (by name) the domains from the Exchange server, so I don't THINK it's a DNS problem, but I could be wrong.

While investigating the first problem I found several emails stuck in the outbound queue for oddball domains with no originator listed. The recipients look like random letters. Is my server somehow being used by spammers?

Thanks

 

[tgentry61103]

I'm continuing my investigation, just jump in anytime.

I did NSLookup and can ping by name and telnet to port 25 of mx1.mail.yahoo.com as well as mx2, mx3 and mx4. I always thought if I could do this I could send mail.

I cannot ping anything AOL although NSLookup works. I can't even ping them by number so I think I know where to look on this one now.

I'm heading back in... cover me!!!!

 

[tgentry61103]

I'm still talking to myself here.

I CAN telnet into AOL mail servers. Apparently they are blocking pings.

So, it looks like the same issue for both domains. I can telnet into port 25, but mail is still hanging up in my outbound queue.

Please shed some light on this for me.

 

[Dyadmin]

Dude, settle down, if we the user don't answer that doesn't mean excluding you. It means we either don't have an answer for you or your problem is new and we are looking for info for you. No need to spam. Next time I won't answer a post like this as it shows, low maturity on your part, as I see it in my view. Show some professionalism!


To answer your question....

Network resolutions happen because of 2 things, your ISP is have dns trouble sourcing the mail mx or a recs *or* your server is being timed out from connecting to those domains you are trying to reach. Maybe you're blocking those people by doing some mail filtering, maybe you're filtering an entire domain. If you were having trouble sending to those people, call them up and ensure that they are alright.. if they are look at your isp and troubleshoot with them. They can have it figured out in no time, if its your or them. I would check your message filtering and connection and relays. I'll put my money on the ISP or a message filtering issue.

 

[tgentry61103]

Dyadmin,
Thanks for the suggestions, so far my ISP hasn't been much help. Since I can telnet by name or number I thought that ruled out DNS issues.

Sorry if I offended anyone. I didn't think I was being ignored, that was just my sense of humor showing. The multiple messages were just an attempt to add information that could be important to a resolution. Unfortunatley I don't see any way to edit posts on this forum or I would have taken that route instead of replying to my own messages.

 

[dennisbbb]

Big isp like AOL, Microsoft, Earthlink, etc.. update their servers and DNS entries from time to time. When that happens, all records are propagated thru out the internet, which requires 12-48 hours time. The fact that you can telnet 25 inward doesn't mean that their servers are available to receive mail. You can resend again using a different DNS entry, to expidite the process.

Another thing might be related, a spam NDR may be routing toward the "Header To" (aol.com) address, but in fact it is really going toward the "Mime To" address. If you take a look at the content of the queue, you might be surprise at what you see.

In your case, if your mail goes out to most domains, then I would just sit back and wait for the queue to time out, otherwise, try out some of those other DNS numbers you can get from other ISP such as Charterpipeline, Earthlink, or even AOL's.

 

[VortigernWolf]

Hi

Just to make you feel better, you are not alone. I have been fighting this problem for months. Here is a link to a forum that I have been following to help me.

http://forums.msexchange.org/ultimatebb.cgi?ubb=get_topic;f=18;t=000384

Seems lots of people are suffering from this. I may have finally cracked the fault today when I set up another SMTP connector and used the ISP relay in the forward all mail through option.

Vortigern