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Failing to secondary smtp?

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jjjax

MIS
Sep 25, 2002
114
US
Sorry if I don't have a lot of details but just wanted to put this out here to see if anyone might be able to point me in the right direction. We are running exchange 2000 server and we also have gfi mail essentials anti-spam and a watchguard firewall. One of our business partners is saying that they are having problems sending email to our primary address because they are getting invalid character type message, something about /r characters and they don't allow it to fail to the secondary smtp, which from what they explained sounds like our isp's address. They say that we might not have noticed this with anyone else because most people aren't that strict and let it fail over but they don't. I never even realized that we had a secondary smtp so I am confused and everything goes through our firewall which only routes the one address to our smtp server so I can't see how if can be come through a secondary one? I tried looking at our firewall, anti-spam and exchange but don't even know where to start and they aren't being very helpful. Sorry that I can't be more specific but I'm just hoping for someone to point me in the right direction. Thanks, Joe
 
Common problem actually Joe.

Start RUN
cmd
nslookup
set server 195.92.195.92
set type=mx
yourdomain.com

(by yourdomain.com you need to put in your domain!!!)

This will return your MX record priority list. MX10 should be your public IP for your firewall. MX20 is probably a mail relay at your ISP.

Check that the MX10 IP address resolves to mail.yourdomain.com and not something_rubbish.2.3.4.yourISP.com
 
It has MX10 as our ISP address and MX5 as us instead of 20 and 10.
 
I ran it using the online tool at dnsstuff.com but not sure what I am looking for?
 
If the IP address resolves to your ISP rather than you they may not be able to send. Think about it...

You are a server set to send an email to yourdomain.com

You look up said server.
MX5 mail.yourdomain.com
MX10 mail.someWierdISP.com

You send to MX5 no problem. But MX10 is not someone you want to think about. SHOULDN'T be a problem but apparently is.

Resolution: Ask this pain of a company to edit their local DNS to include your TWO MX records so that the problem goes away. Their SysAdmin should be able to do it in less than 2 minutes.
 
He finally put in a static route but gave me a little more information. He said that our primary smtp server is sending "double line ending character that kills the smtp session". I still can't find much information about how Exchange 2000 does this. Thanks, Joe
 
jjjax,

Do you have the SMTP proxy enabled in your WatchGuard firewall? I'd start there, as WatchGuard filters all SMTP connections to your network and might be the culprit...Let me know how it's configured, as I'm an Exchange 2000 and WatchGuard engineer...
 
Yes, we do have the smtp proxy installed on watchguard. We just have it forwarding from our internet i/p address to and address on our network for our exchange server on port 25. It's been basically the same for the last 5 years. I believe the only other thing that we played around with when setting up was adding some more extension types to be blocked. It's been hard getting more information from them but I might have another person having a problem but not sure yet. Thanks, Joe
 
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