Outbound messages not delivering

[MB10]

Hi Folks,

I'm running exchange 5.5 SP4 on a Windows 2000 box.
I have a number of outbound messages stuck in my queue awaiting delivery with <Host Unreachable> as the error message. I can reach the hosts mail server (using nslookup and ping) but the messages are not delivered. I can reach the same addresses from my hotmail account.

How can I get these messages delivered or how do I check if the problem is with my server to begin with.

Thanks for the help

 

[Zelandakh]

could be a DNS issue. On the Exchange's DNS box (probably same server), go to command and use nslookup. Do set server= and use the ip address of your ISP's DNS. See if that cures the trouble.

 

[ricor]

Did you get this resolved? I'm running into this same problem for some of our clients. I have noticed that the clients are ones who do not have MX records listed on their DNS provider. It seems that Exchange is not so good at dealing with wildcard lookups of MX records or something like that.

 

[MB10]

Nope. Still the same issue. I tried pointing Exchange to a different DNS server but got the same result. All the clients have MX records listed so I'm stumped. I double checked all the settings I could think of.

 

[epsom]

does any of the mail youi are trying to send have a format with double dots that is anyone.nancy@go.net

 

[MB10]

No. No double dot names. Our default reply address has firstname.lastname@company.com but none of the recipients do.

 

[yunit]

Did you try and telnet to port 25 on the hosts to make sure you can get a valid connection?

Check the Connections tab and make sure that Transfer Mode is set to Inbound & Outbound.

Are you using and internal DNS IP or an external DNS IP? Use an external IP.

Is this server behind a Proxy?

Maybe try deleting the Internet Mail Service and recreating it, but do not make any changes excepting Routing for incoming email, then re-running SP4.

 

[MB10]

I can reach clients via telnet on port 25 and Transfer Mode is set to Inbound & Outbound. I am using an external DNS server and the Exchantge server is behind a firewall but all relevant ports are open. My problem is that this only affects a small number of e-mails per day. I can see no pattern as to which e-mails get stuck and which don't.

 

[RFNHOUSTON]

I am having the same exact problem on my email server. I am running Exchange 5.5 w/ SP4. It is running on Windows 2000, but I have had this problem when it was on NT 4 as well. This problem is really annnoying as nothing I have tried has seemed to fix it. I have tried numerous things, removing and re-adding the IMC, changing my DNS to internal, external ISP, and even setting my DNS to MS's DNS servers. Nothing I have tried has worked. If anyone can find a fix I would definently appreciate any help.

Thanks!

 

[napoleao]

I have exaclty the same problem, We have Exchange running on NT4 and every day we have messages stuck, sometimes more sometimes less.
My first thought was dns, i have tried few things but its still the same. It can be very frustring when you have the director of the company calling you because he has not receive his emails.

 

[napoleao]

I have solved the problem, for now probably .
Go to the configuration bar inside connecitons and then there you should have something there called SPECIFY EMAIL DOMAIN.
Go inside and then click ADD, enter the EMAIL domaina then the check Foward all messages for this domain to host: then enter the ip.

I did solve my problem this way, maybe it will work for some of you as well.

 

[MB10]

I have quite a number of domains that would have to be routed that way. I sure hope there is a permanent solution to this somewhere or else I'll end up managing a seperate routing table within Exchange

 

[RFNHOUSTON]

MB10,

I have the same concerns you have. If this was only happening on one or two domains then it would not be a big deal, but this isn't just one or two. We are talking different domains on different days. Some as big as swbell.net. If anyone has found any kind of fix please let me know. Thanks!

 

[MB10]

I think I may have it solved

After spending two hours on the phone with MS it came down to a trailing period on my DNS name. Apparently some recipients are perticular about correct DNS suffixes. Make sure that you have a correct and valid name setting as your DNS suffix on your exchange server box (such as domainname.com set in system properties, network identification). Our was domainname.com. and it caused some EHLO and HELO errors in the logs. If you want to see if this is the problem, just set your SMTP protocol logging to maximum and search the log files for EHLO and HELO errors (501 and 511 I think).

Hope this helps

 

[yunit]

Also, some companies do not accept different forward and reverse DNS entries on their firewall. So this will just drop the message not allowing it to be delivered.

 

[RFNHOUSTON]

MB10,

Thanks. I did not have anything in my DNS suffix. Added it and it did take care of about half of the 10 or so emails I had in the queue that were there for several hours. Still trying to resolve some otheres. Thanks again for all the help.

-Ryan

 

[MB10]

I also had to add a reverse lookup for the exchange server to my DNS to resolve one or two problem domains. I appears that they do a reverse lookup before accepting any e-mails.