Exchange / SBS 2003 strange mail issue

[DavidSnell]

We have recently moved our mail in house from our ISP. (They previously provided us with pop3 access)

It's been configured and running for 5 days now with one issue. Some email is successfully delivered to my users and some is not. Here are the particulars:

MX records are updated and listed correctly.
My ISP provides my backup MX record in case my Exchange server is offline. (this backup server is in fact receiving the email that I don't get)
We can send email to anyone with no issues.

The STRANGE things:
We can receive email from AOL users and many other domains with no problem.

When I DON'T receive an email I am expecting, I can send that person an email and if they "Reply" to it, I get it with no problem.

I am at a loss here. Receiving some but not all mail is very confusing.

Also, I should add that we have been using Exchange internally for over a year now with no issues so this is not a new install. So I am looking for a direction to go with trouble shooting this problem

Thanks in advance

 

[dkediger]

Well, the fact that your ISP is receiving the mail not passed on to you indicates a problem with their setup and handling of DNS * OR * congestion on your bandwidth to your ISP making it think that your server is unavailable.

High utilization on your SBS server could also make Exchange unresponsive to incoming mail.

What % is getting redirected?

 

[DavidSnell]

It looks like about 30% being re-directed. What confuses me is that someone can reply to an email sent to them and I get the reply - but I don't get the mail if they just send it on their own.

How would I check the utilization of my SBS server?

If it helps with diagnosing, the domain is GoAmerican.com and DNSreport.com looks OK according to my Web host.

 

[Marcs41]

Hold on a minute.

That sounds alot like a DNS issue, but not on your end.

What dkediger is saying is 100% correct, but there is another potential issue.
If your contact uses their own DNS server, or their hosts, and THAT one is not updated, you will indeed see what you are seeing now.

When they send, they use THEIR DNS settings to find you, hence, the 'old' settings, your ISP.
When they reply, they use YOUR settings that are IN the header of the mail you just sent them, so, you will get it.

Marc
[sub]If 'something' 'somewhere' gives 'some' error, expect random guesses or no replies at all. Please specify details.
Free Tip: The F1 Key does NOT destroy your PC!
How Do You Get Great Answers To my Tek-Tips Questions? [/sub]See faq222-2244

 

[DavidSnell]

I agree that it sounds like an external DNS issue. I think it's unlikely (but certainly not impossible) that some DNS servers have not updated their records yet (5 days since the MX record change).

If that is the case I should see the amount of mail picked up by the server at my backup MX record diminish over time.

I am looking at my ISP now to see if congestion might be the issue or maybe they are filtering incoming mail traffic in some manner causing it to be bounced to the backup system.

If you have any additional thoughts please let me know.

 

[Marcs41]

Unlikely? No, I have seen worse.
Unbelievable? Yes, but true.

Some companies set up their servers in such a bad way that their DNS just never updates. Whatever is in there, stays there, and then things like this happen.
I have seen it many times, it may not be the case here, but it sure sounds like it.
The problem in such a case is, someone, in this case you, is looking for a problem you cannot get your finger on, simply because it is not your problem, you just get the consequences.

You don't really mention how many 'other' domains you have problems with when they send you, as so far, you just mention that one friend.

To check my 'claim', do the following.
Have your friend send you a message directly with subject '1'.
Then send him one with subject '2' and have him reply.

Get message 1 at your ISP, where it will comes as you state and message 2 (the reply of course) at your server.
Then compare the headers.
I almost dare to bet you will find in message 1 the 'old' MX record address, originating from your friends mailserver.
IF that is the case, you need to check with your friend where he get his DNS from, and have him fix that.

Happy hunting.

Marc
[sub]If 'something' 'somewhere' gives 'some' error, expect random guesses or no replies at all. Please specify details.
Free Tip: The F1 Key does NOT destroy your PC!
How Do You Get Great Answers To my Tek-Tips Questions? [/sub]See faq222-2244